Your mainboard will not support more then an UDMA 33 or if its a later chipset UDMA 66 hard drives. The ATA100 drive mentioned above will "work" but will slow down to 5400rpm and ATA66 speeds to be compatible with your system. Additionally, your board may be using the dated SDRAM RAM, not even the now dated PC100 type. SDRAM will only run at 8-10ms on a 33Mhz bus (circuit) so more RAM then you have might actually begin to degrade performance. Even more RAM with PC100 type RAM on a 66Mhz bus will not benefit you more then what you already have.

If you have one of the later chipsets and Boards you may have an AGP graphic adapter. However, I would suspect the graphic adapter is PCI format or even integrated on to the mainboard in which it cannot be changed. Even if your graphic adapter is AGP it is v1 compliant and will not support the new graphic adapters (video cards).

Bottom line is there is precious little you can do to increase the system performance via hardware. What you need to do is simply close anything which runs TSR (in the background). Although they may not be active they may take processing cycles simply to hold open. If your offline, then close any firewall, virus protection, additional function features like mouse control panels, scanner and CD writer controller software which often runs in the background. Doing things like that will help your stability and give max processor cycles to renders etc.