8 years is quite a long time in computer life, +1 @Fugi & Masherbrum.
Denniss has a point, too, but I'd like to take the idea one step further. The X300 is at the low end of Radeons of its era, but instead of a much newer card I'd look for a second hand high end card of the same age or one or two generations younger to be in par with the rest of your system. You can get an X850 on Ebay for around $20, an X1950 for $30 or an HD2900 for $45 which shouldn't be too big an investment. Something like that might give you time to save for a good AH rig for the next 8 years to come. If not, it still would run old games like a charm.