From the specs that I saw, it looks like the x300 is below the 9800Pro in performance quality. Not by much, but still.
Do you still want to stick with ATI? And is your motherboard AGP or PCI-E?
Okay, I just saw the thing you wrote about money. Well, I would take his x300 if he is giving it to you for free, but make sure it's an AGP card, and not PCI-E. Use for a while and save up for a x850XT or something like that.
<font size=1><b>Current Build:</b>
DFI Lanparty Ultra-D
<a href=\"http://valid.x86-secret.com/show_oc?id=77714\">AMD 64 X2 4400+ @ 2.20GHz</a>
Big Typhoon Heatsink/Fan
2 GB G.Skill DDR500 PC4000
eVGA 256MB 7800GTX
2x 120GB Hard Drives</font>