Recently the NVIDIA card on my Alienware laptop died out, and since the system is a few years old already, I am unable to find a replacement swappable NVIDIA card...
 
As a compromise while I save up for a new laptop I'm trying to spend a small sum of money to build-up a nearly unused few year old DELL desktop system to nearly the performance of my older Alienware laptop (currently, it's far from it).   The laptop was a Pentium4 3ghz hyper-threaded with 1MB RAM.
 
I know very little in terms of specifics about the innards of computer hardware.
 
I'm looking to spend around $300, hopefully, and go this cheap by using components of the DELL desktop that I already have, if possible (That is for you guys to tell me).  Below are the system specs on the system, processor, motherboard, et cet along with some images of the case/mobo/fans/etc.
 
Please throw your best suggestions out as to what I can do with it all. Processor upgrade? Ram upgrade? Full mobo combo + ram upgrade required? Do I need a new fan? New CPU fan? Where should I get the gear?
 
What should I get to make the biggest bang for my buck with
all the DELL existing compontents taken into mind as well.
 
Thanks in advance =)
 
 

 
 
Case:

 
Inside:

Upper inside:

Lower inside:

Back:

P.S. A good additional bit of information I neglected, my intended computing purposes:  
 
Despite having had an Alienware I'm not a gamer at all, I was simply looking for a solid reliable high end speedy desktop-replacement style laptop. I'm a developer/programmer mostly, so nothing super intensive, other than the occasional Photoshop and super occasional Premiere video editing. Most of the time I'm just working within Visual Studio or with WAMP (running as a personal server), etc. If it seems like this system is suitable for the tasks I just mentioned, it actually isn't at all. . I don't need a whole big performance upgrade to get geared up on Bioshock or something, but as much as I could do to make the system more responsive would be great.
 

About the only thing you're going to be able to salvage from that old Dell is the CD-ROM drive. The case, motherboard, and power supply are most likely all proprietary. Unless you already have an operating system disk to load onto a new system, (easily 1/3 of your $300 budget) or you're willing to switch to some flavor of Linux, you'll be hard pressed to build a system for $300.
 
Here's what I did come up with. By no means is it a screamer, but it should function well enough:
 
Case/Power Supply - Raidmax xB ATX - $22.99
Motherboard - ECS K8M890M-M - $32.99
Processor - AMD Athlon X2 4000+ - $57.99
Memory - PQI Power 1 Gig (2x512Meg) DDR2-533 - $15.99
Hard Drive - Hitachi 80 GB SATA 3.0 - $42.99
Graphics Card - Chaintech Geforce 7600GS PCI-Ex16 - $104.99
 
Total in cart - $277.94
 
-Wolf sends

Thanks Wolfshadw.  
 
The $300 price range was a product of envisioning myself as already having a system in which I can upgrade existing components that I already own. In light of the proprietary nature of this box and even the RAM possibly being maxed out at 512, I'm starting to realize my best bet I suppose, is to buy a build a completely new machine, case and all.  
 
So, my price is more flexible, although for a temporary system I'm still trying to keep it low, but I certainly need something for now, and I'd like to get the best bang for my buck as well if I'm looking to spend more.
 
How much money would I be looking at to make a system that could run, at very least as well as my P4 3GHz 1GB RAM Alienware laptop?  Any further suggestions from the expertise of this board as to the package of components I should purchase to build this system (and from where) would be extremely appreciated.
 
Thanks

the case looks like it can fit a atx board
 
also get a better MB then the via one nforce 570 boards are about $70
 
also 1gb is too low go for 2x1gb for about $40+ after RB
 
also you can get a 2600xt for $100 with dual DVI
 
you also need a good psu the ones that come with the cases are most carp.