Well if you can, I think you need at least 512mb, especially when running WinXP. Your system may be bottlenecking because of the ram.
Well here is the FBS change
1. Open up your CPU's BIOS settings page. Find the section that controls the front side bus speed.
2. Turn up your setting by a small increment, say 5 percent to 10 percent of your processor's rated speed.
3. Boot the computer. Does it boot? If no, then you turned the clock speed up too much.
4. Keep an eye on the temperature of the processor. A hot processor is a soon-to-be-dead processor.
5. If it boots properly and the temperature isn't too high, repeat steps 1 and 2.
6. If the computer doesn't boot properly, turn the settings back down to the last stable setting.
7. This is where more experienced overclockers might start turning up the voltage supplied to the CPU, or trying different memory, or more cooling. Think twice before you jump in. You can blow a chip, and, like drag racing, it tends to get addicting.
8. Boot the computer and run several different applications. If they run fine, then the computer is fairly stable.
Source: TechTV!!!!!
http://www.techtv.com/screensavers/answerstips/jump/0,24331,3358489,00.html