My setup. How high can I go?

Barton 2500+
Sapphire Radeon 9500 Atlantis 128MB DDR
2*Maxtor IDE ATA-133 120GB 7200RPM 8MB
2*TwinMOS PC3200 DDR-DIMM 256MB m/Winbond
Abit NF7 V2.0
EKL Blade CPU-fan

Since the Mobo has a fan on the northbridge but I guess it aint so great I was wondering what safe fsb should I be able to get up to without risking to fry the NB and SB chips?

Around 220MHz seems to be a reasonable fsb with the NF7-S v2.0. The nForce chipset runs much cooler than any of the recent VIA chipsets and your northbridge temperatures should not be a problem. You may have to increase your chipset voltage in order to reach the 220MHz range with stability.

I am not familiar with your cooling choice, so I have no idea how well it will work.

One component that you DID NOT list can have a limiting effect on any overclock: POWER SUPPLY.

The power supply is a Thermaltake 450W...