Depends what mobo you have but usually under the CPU specifications tab or system specs but install CPU Z it's free and it'll tell you what your CPU is running at and a lot more stuff about your system there's also GPU Z also.
Thanks for reply!
So...my system is:
Mobo name:Hewlett-Packard HP Compaq dc7700 Convertible Minitower
Mobo chipset:Intel Broadwater Q965
CPU: Core2Duo E6600
RAM: 3,5 GB (667 mhz freq)
I can't find the settings in bios where to set the fsb...
Your probably not going to be able to change the FSB because the you bought it from HP. Typically OEM's like that will not put an option to change it in the bios because they don't want to have to deal with people breaking things. This is why you don't usually see people with overclocked Dell's, HP's etc.