You can get a 64 bit Sempron processor (754 pin) for like 70 bucks or less; the 2600+ Sempron (Palmero Core) on Newegg runs about that, and maybe 70 for a mobo.
A lower level 939 pin (Venice) AMD 3200+ runs a bit more; like 140-ish.
http://www.newegg.com/Product/Product.a ... 6819103535
a compatible mobo runs 100 bucks or so
http://www.newegg.com/Product/Product.a ... 6813128306
it's SLI capable, but I'm not terribly fond of SLI (I don't have the $$ for two GPUs). But, it's got 4 DDR slots, for up to 4 GB RAM, 2 PCIE16X (duh), 2 PCIE1X, and 2 PCI slots. Raid functionality is included, for RAID 1, 0, and 1+0. Up to four SATA drives, etc. It's the SLI version of my mobo
There's tons of USB ports, decent integrated sound, it's a very nice board. I do wish I'd gotten the SLI one myself, and kick myself daily for going with the non-SLI variety. Although, I'm not sure why.
you actually get a decent price break buying them together. The mobo supports the X2 series as well. As another dude said, it's not worth it yet; IIRC the processors are still in the 1 grand plus range, and damn, most of us don't have that type of cash. I'm thinking by the end of next year they'll have plummeted, and I plan to pick one up then myself.
I think you're still out the RAM, as yours is that funky intel stuff, but you can get a few sticks of that cheap too:
http://www.newegg.com/Product/Product.a ... 6820145450
hey, a gig is better than 512, right?
It totals closer to 400 than two, but why pour money into dead tech? AMD currently spanks Intel in the gaming department.
I just recognized that you have an AGP card...errr....don't know. That adds some. But you can find 6600GT PCIE for 150:
http://www.newegg.com/Product/Product.a ... 6814150098
I think if you search newegg more, you can find them down to 130 or so.
If you want to try an ATI variety, an X800GT runs about the same.
all told that's...140+100+150+120=510. Double what you were planning on, but much nicer than the old system post-upgrade. Sell your old stuff and do it.
edit for math.