I have a Windows 7 desktop and I can either get Fritz 12 or Fritz 13.  I know there are more features in Fritz 13 and it is certain to work on Windows 7, however I can save $10 on Fritz 12 and it has almost the same features, however I'm not sure if it works on Windows 7.  I am a club player by the way.  

Fritz 12 works on my Windows 7.

f13 is much better than 12, fwiw.

Nothing personal, but judging by your rating I don't think what version you get will matter much insofar as F13 being better than F12.  I'm rated 2125 and I doubt if upgrading to F13 would help me, I already have F12 and it's pretty awesome; but on the other hand, if the $10 isn't a big deal I'd go with the latest and greatest version. On the other other hand, you can definitely save a lot more than $10 if you shop around at amazon and eBay for F11/12/13 and you can figure out the difference between F13 and F13 Chess (sigh, why do they have to deliberately confuse us?)

Good luck!