You can purchase a 1000 MHz (1GHz) Processor from:swrobbie said:
lacc.com/product.asp?pf_id=K7100MNR53B
Also for your information the motherboard will take and recoginze 256 RAM PC 100 or PC 133. purchase quality RAM from Crucial:
crucial.com
Cruial also has a scanner that you may use to scan your system and let you know what the max is (768). But if you look it up by make and model it will state 384. Iv'e tried and it works and system verifies. I'm running at 640 right now (256, 256, 128).
I have thought about trying 512, but I have not tried, no real reason or need for it.
DMS also has memory that works well and is less expensive:
datamem.com/viewcat.asp_Q_C_E_756
256MB 168 Pin PC100 32X64-8 CL2 Unregisterd SDRAM DIMM (16 Chip)
Just make sure you use low density chips (16 chips).