As I get my dual Ubuntu / WinXP box running, I learn of software my daughter would like to have under Linux. She uses Photoshop in Windows while I prefer Arc Soft PhotoStudio 5.5. (My needs are very simple.) How close does GIMP compare to Photoshop? To PhotoStudio? What's the learning curve?
Thank you.

It really depends on what you want to do.I have never used windows and neither have my kids so its always GIMP that is used.There are many tutorials about using GIMP on the net.Its hard to advise as I have never used anything else but I find GIMP fairly easy if it is just basic manipulations e.g brightness,contrast etc.GIMP is a massive application with many addons/plugins available.If you are using dual boot why not try it out while following some tutorials.If you don't like it go back and use what you prefer on your windows partition.

The GIMP is almost on par with photoshop (considered the best image editing software, so I assume it is superior to ArcSoft in term of features) in term of feature, but the GUI is lacking. It is much harder to use and the dialogs are not that great. GIMP 2.8 will solve many of these problem, but it is in alpha right now (2.7.*). You have two choices, learn 2.6 with some tutorials to find where the buttons are or install 2.7 ans turn on the Single Window mode in the Window menu. Then it will be more tolerable with dockable palettes and some gui improvments. The only "big" feature GIMP is missing is advanced color modes.

You can also try Krita, it is much simpler, but more oriented for drawing and content creation than content correction like PhotoShop. It worth trying anyway.

There is no product close to the current Adobe Photoshop period. It is the best and used by the best creative shops in the world because it is what they need. That doesn't mean that you can't enjoy and use effectively an open source app such as gimp. If you want you can try the portable app version on a flash drive on windows. See portableapps.com for John's unique approach to usb apps.

I can use gimp all day long, but I have spend a lot and I mean a lot purchasing Adobe's products for my wife's company as well as training for her. She is a professional in photography and works on many creative projects.

There would be a limited learning curve. Most tasks are similar in concept but may have name changed. If you can describe the task you can use help in most cases to get what you want out of gimp.

Photoshop is good but GIMP is still the tool of choice for me. Tool size picking and alpha management are plus. Color management as well. It also has lots of powerful plug-ins contributed by the community. I find it a lot easier to use GIMP than Photoshop... But that's just me.