i have a gateway, p3, 733 mhz and 256 ram, and i have a XFX GeForce FX 5500 256MB DDR video card.. i kinda wanna play modern games.. but im on a very low budget
You might want to consider haveing atleast 500-600$ budget to start palying modern games; that what i used to do:
with 600$ get:
A DFI mobo 100$
A 3200+ amd 150$
one stick of 512 ram ( YOU CAN UPGRADE IT LATER) 25-35$
A 6800GT vedio card 100-200$
Use your old case (free)
Get a crappy psu that supports pci express (40$)
that's all you need, you can upgrade the ram and other thing you don't like later.