Winxp sp update problem

[boondocksaint]

:( Heya
Im having problems updating to sp1 I got this windowsxp disk when i was at college from the actually school
So I think its legal
Heres the error message I get

setup has detected that the build version of the system installed does not match the update you are appying to it.
you can only install on build 2600.

any help would be really welcome
------
My specs
Athlon xp 2100
Epox 8ka sumtin mobo
1024 pc2100 ddr
Geforece 4 ti4600
SbLive! 5.1
Wd 7200rpm 160g hd

[G Smith]

Any chance you have a beta version? Build 2600 is the final XP build.

Check what version number you are running by going to System Information.

Start-->Accesories-->System Tools-->System Information