Hi, im about to upgrade my old P4 and i have to say that im kinda confused with new computer parts so here i am asking for advice.

I want to build a cheap gaming machine with an intel processor and a nice motherboard (w/o SLI or CF). Ive been doing some research which takes me to the intel P43/P45 motherboards but... does someone know the difference between P43 and P45? which one is better?

There's also two available south bridges: Intel ICH10 and Intel ICH10R.. does the ICH10R has any advantage over ICH10?

Now when it comes to the memory there's a couple of questions too.. do i have to match the FSB of the processor with the memory frequency in any way? if the motherboard has a DDR2 XXXMhz memory standard do i have to buy that XXXMhz memory?

The "R" south bridges have RAID support. You might consider the not-so-new but excellent Gigabyte P35 MBs: GA-EP35-DS3x series. Otherwise, I'd go with the GA-EP45-DS3x series.
Regarding the FSB, divide its datarate by 2, then run your memory at that speed. For example, for a CPU running at a 1333MHz FSB datarate, run the RAM at DDR2-667. For a 1600MHz datarate, run the RAM at DDR2-800. The MB memory "spec" is just the fastest RAM it can run; slower is no problem.

Thanks A LOT Mondoman, but now i have one last question

I want a cheap 8800gt but the P35 does not support pci-e 2.0.... is Pci-e 2 backward compatible with pci-e 1? will the 8800gt run OK in a pci-e 1.0 without any performance limitations?

Thanks in advance