WSS 2.0

Here are the respective version numbers (specified in Site Settings) to help you with this:
 
- 6.0.2.5530 - WSS
 
- 6.0.2.6361 - WSS + SP1
 
- 6.0.2.6411 - WSS+SP1+Security Fix (KB887981 / 8thFeb 2005) 
 
- 6.0.2.6568 - WSS + SP2
 
(- 6.0.2.6551 - R2 WSS (SP2 equivalent) [still in Beta])