Basically, I have the EXACT same problem as...
Just purchased it, installed and immediately downloaded the 1.41 patch. Can't join any servers, always says I have an older version than the server I'm trying to join. It says it installed but it's not showing up in the top right.
Specs incase needed: 2.80 GHz Pentium D processor 1GB of RAM Nvidia 6600 GFX card Windows PRO
Have you tried restarting your computer since you installed the patch? You may have already done that but just checking :)