Re: GIMP is, or at least has been enough of a match for most of what PhotoShop did
The problem with the "Photoshop vs Gimp" argument is that Gimp is likely adequate for what a large numbers of users need it for. If you're a professional illustrator, or perhaps even one of those clipart-wranglers that likes to pass themselves off as a graphic designer, then yes, you most likely need Photoshop. But if you're at that level of professional usage, you should probably be using a Macintosh anyway (which this precludes another MSWin/Photoshop user).
A large percentage of Photoshop users just don't need all that power. It's like those folks who have a Hummer (or Range Rover, I guess, for those of you in the UK) to drive 2 blocks to the local Starsucks for a foamy latte. Complete waste of money and horsepower.