Apocc Rooster :
So I just got an EVGA GT 240 512mb Superclocked. I was expecting high SC2 settings, but they're all recommended at medium. I've heard this card can do more. My other specs:
CPU: Pentium D 2.8Ghz
RAM: 3GB, old, cheap, mismatched
Interface: PCI-E 1.0 (I think)
G-Card: See above
What's my bottleneck? Upgrade vs. save for a new computer?
The bottleneck is BOTH the processor and the graphics card. I myself have a 9600 GT card with e4500 core 2 duo, and although on ultra settings everything works, there's occassional slowdown and somewhat long load times.
Is your computer a custom build or namebrand? If namebrand, you'll need to go on the forums of the respective manufacturer because its possible they lock the motherboard to support certain processors.
If your willing to spend at least $300, and the graphics card is returnable, and this is a custom build, I'd get a new motherboard with an lga 775 (for Intel Processors), then get a processor with at minimum 2.4 Ghz clockspeed (as per Blizzards preferred system requirements). Although they are trying to phase the socket out, you can still build a powerful rig with them. You can basically go up to the Core 2 Quad family processors. If the RAM is not DDR and is DDR2, then just be sure to get a board that supports DDR2 and you can reuse parts. Check power supply specs to make sure it meets minimum of graphics card requirement + little more to account for other components.
If your not a PC builder, on a budget, and/or want to work with what you have, check manufacturer forums for supported processors. A core 2 duo is a must for this game to avoid slowdown, but don't quote me on that being the absolute minimum because I myself am having some occassional slowdowns with a 9600 gt, 2 GB ram, and core 2 duo e4500.
Honestly, if saving for a new computer won't take you that long, thats the best route. All dependent on what you are willing to spend. If you want to put a dollar amount to reply I can help ya out specifically.