[whiterabbit]

Photoshop is necessary, but in my experience CS3 is usually adequate. CS5 only becomes necessary due to lock-in.

I use GIMP whenever possible. That's maybe 50%. The UI is maddening, but this is a big step in the right direction:

http://news.ycombinator.com/item?id=2890397

[katieben]

Hmm, what do you mean by lock-in?

I've tried GIMP, but the maddening UI you mentioned just isn't worth the frustration to me..

[whiterabbit]

It's not possible to read a CS5 PSD with CS3. If you don't follow Adobe's upgrade path you're out of business (which means a great opportunity for GIMP).

http://en.wikipedia.org/wiki/Vendor_lock-in