Not trying to sound rude, but just because your's crashed doesn't mean hammer as a whole is a program that crashed frequently.
Everyone has different operating systems man.
I heard something about windows 7 having problems with the SDK.. Do you know if that's still an issue?
Edited:
It depends on what you're trying to achieve and what your actual requirements are. Go watch War Of The Servers if you want to see what gmod is capable of in terms of machinima making.
Note that 9/10 of the movie was made in Gm9, the highly outdated free version of gmod. You have to pay for the current version, but it offers so much more options that you can hardly compare the two. Not to mention that version 13 which is in beta stage atm will be released soon, adding whole lot new functions, aimed mainly at machinima makers.
Alright... My requirements aren't that high, just to be able to use custom maps. I appreciate the heads up about Gm13 though, and thanks for the info about War Of The Servers.. It looks pretty cool from what I've seen already.