So long as the final product for youself or the customer is top quality (only you can produce) and the client is happy with it, it doesnt matter what you use ed
I use Photoshop CS2 and Macromedia Fireworks 8 (Adobe hadn't bought Macromedia when Fireworks 8 was released). I've begun to use Flash which I know will prove to be an important weapon in my arsenary.
I use Fireworks to perform simple tasks and Photoshop to perform the more complicated tasks. I plan to top the design off with animation and sound from Flash in the near future!
I can't get used to the interface of GIMP - I probably should though, there are so many people evangelising it.
I tend to avoid graphics work as much as possible - even to the extent of just using template software like Xara webstyle. Graphics are not my strong point.