I think the card and the cpu match-up OK. In other words, i don't think an 1800+ is a big bottleneck with a 9600pro.
For a while I ran with a 9600 pro and a Barton 2500+, the card was what was holding me back in games.
If you're worried about the cpu, yeah OC it a bit. Hopefully your mobo has an AGP/PCI lock so you can up the FSB. I would think any decent PC2100 could handle some OCing. You may have to up the vdimm (voltage to ram) or relax timings a bit.
Use Memtest86 to test the ram for stability (a free proggie, just google it).
Same as above for Prime95 to test the cpu for stability when OCing
Mobile XP 2600+ (11X200)
Abit NF7-S v 2.0
Maxtor 60GB ATA 133 7200RPM
512MB Corsair Twinx 3200LL
BBA 9800 Pro
Enermax Noisetaker 420 watts
Win2K sp4