Initial Selection:

• $90 -- GIGABYTE LGA 775 Intel P35 ATX All Solid Capacitor Intel Motherboard
• $110 - Seagate Barracuda 7200.11 500GB 7200 RPM SATA 3.0Gb/s Hard Drive
• $90 -- ENERMAX Liberty ELT500AWT ATX12V 500W Power Supply
• $45 -- G.SKILL 2GB 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Desktop Memory Model
• $180 - Intel Core 2 Duo E6750 Conroe 2.66GHz LGA 775 65W Dual-Core Processor
• $30 -- Creative Sound Blaster SB0570 Audigy SE 7.1 Channels PCI Interface Sound Card
• $80 -- MSI GeForce 8600GTS 256MB 128-bit GDDR3 PCI Express x16 HDCP Ready SLI Supported Video Card
• $55 -- COOLER MASTER Centurion 5 Black/Silver Aluminum Bezel, SECC Chassis ATX Mid Tower Computer Case
• $9 --- Logitech 967740-0403 Black USB Standard Internet 350 USB Keyboard
• $689 - total

What I can reuse:

• DVD-ROM gdr8163b ATA Device
• Samsung Spinpoint 500 GB harddrive
• Logitech wireless mouse
• XP professional 32-bit and Vista Business 32-bit CD's free from MSDNAA
• 22'' Acer LCD

Activities:

• Havn't played games in 2 years, so will probably just play outdated games no more demanding than Unreal Tournament 3.
• Mostly 2D graphics design and web design
• Music listening

Questions before I buy:

• 1) I'm planning to install XP (with minimum partition because I only need to run one program: Internet explorer 6) and Vista on the fresh new harddrive (which I will use 90% of the time). Is this hard to do? Can the partition be made before any OS is installed?
• 2) Are the above brands known for giving good drivers for both XP and Vista?
• 3) Should I get a mobo with SLI support? The reason I did not choose to get one this time is because SLI disables dual screen. Will it support dual screen in the future?
• 4) Most importantly, does the PSU and mobo support all those parts? I'm not particularly sure what connection my old DVD drive needs.
• 5) Is it better to get PSU's with a single high current 12V rail or many lower current 12V rails?
• 6) Does everything come with all I need? Do I need to buy extra wires and stuff?

Looks good. If you plan to OC checkout:
http://www.tomshardware.com/forum/ [...] w=0&nojs=0

Your PSU is good (Tier 2), and has more than enough voltage,etc. Partitioning is pretty easy with Vista. Make sure you install XP 1st and then install Vista 2nd. No need for SLI. Though if this is a gaming rig you might want to take a look in to the 9600. The 8600 pretty much su*s for gaming. You shouldn't need to buy extra wires (though if you have IDE drives you might want to get round cables), and you might want to buy more case fans, CCFLs,etc. If you plan to OC get a good CPU cooler. I heard that Xigmatek HDT-S1283 is one of the best (Frostytech has it at #1). If possible get Vista x64. Every thing you have listed will/should work with each other. Nice job on the overall selection. Good luck.

PS: If you are interested in OCing read the guide, and if you need help just PM me.

Looks like a pretty solid build. The is an excellent motherboard choice. Dont worry about getting a SLI motherboard, since you dont play demanding games and, SLIing anything but 8800's or better is pointless. Partitioning is very simple. Just use the software that comes with the hardrive. And yes you partion BEFORE you install the OS.
Dont get a 8600gt, and dont buy from MSI (From my experiance). If you want to play UT3 it really would help to get a video card with a little more power, especially at that resolution. Can you afford a few more dollars? If you can get this.
http://www.newegg.com/Product/Prod [...] 6814130332
You will be much happier. If not, get a 3650. I like this one. It would be able to play UT3, but not nearly as well as the 8800gs.
http://www.newegg.com/Product/Prod [...] 6814102725
Yes the motherboard and PSU do support all those parts. But, you dont nees such a expensive PSU. This will serve you well.
http://www.newegg.com/Product/Prod [...] 6817139003
Since you are buying everything retail, all cables should come also.
Post anymore questions you may have!!

On that PSU you posted, it has says +12V@33A,-12V@0.8A. Does that mean the single +12V is shaired between the processor and video card? Is it better to share or better to have dedicated rails?

And the PSU that I chose was the cheapest modular PSU I could find on Newegg. I'd like to have it be modular because I have very small amount of components.

Yes the PSU i posted is a one rail psu. There is much controversy over which is better and people have argued over it since the dawn of time lol. I honestly am no electrician, but heres a artical i found a while back that helped me understand rails better.
http://www.pcpower.com/technology/myths/#m8

Well, if you want a Modular PSU, the one you were orignally going with seems great.
What did you think of the VGA cards?

http://www.newegg.com/Product/Prod [...] 6817339012

The OP wanted a modular Quality, Modular PSU.

I will not be able to say which is better since I am inexperienced in PSU design/workings. You can PM Zorg with your questions. He knows best when it comes comes to PSUs.

I just wanted a cheap graphics card, so I picked Tomshardware's March's best card under $100. I'm not into intense gaming and these things get outdated really fast, so..... And I've read that almost all ATI cards use more wattage than nVidia cards of similar performance.

Sorry for going off topic, but in what way is modular PSU better? I'm building a rig too, so it's a good time to ask.

Modular PSU arnt better. The OP wants one because "he has limited componants". Which is understandable. Just letting you know ::
In fact, some say that modular PSU's are not as good as regular ones. I have no idea i just heard that somewhere...

It allows you to use only the wires you need. It avoids clutter. Non-modular PSU's have all the wires fixed in.

Ah, got it. I knew about the removable cables, just thought there might be something more than that. Guess not. As for "worse than regular," I've heard that it's less efficient because some power is lost in the extra plug connections. That seems like just nit-picking though...