Resizing Primary (C:) partition, Windows SBS 2003

[DoubleCheese]

Our SBS Server has run out of disk space! Its a Dell PowerEdge server running SBS 2003. The Primary drive was only partitioned to 20Gb and the remaining 280Gb as storage, but its showing only 40Mb left on the Primary drive.

Is it possible to resize the partition safely (there are a number of drives in RAID5) or is it a case of backup and reinstall with a larger partition?

Cheers.

 

[DoubleCheese]

No I haven't moved anything yet. It has only a few apps installed, Blackberry enterprise Server, MS Office, Ultra VNC and an AntiVirus.

What could I move easily that wouldn't break anything?