Try Winrar,bat-sof2.rar is a rar after all.
I just ran into a problem where I couldn't extract SOF2...It was really starting to bug me too. So finally after screwing around for about 2 days I Upgraded my WinRar to Ver.3 and thats all it took.
Links
http://www.rarlab.com/
Crack
http://www.andr.net/filez/w/WinRAR_3.00_final.zip