How about getting rid of Windows Vista to start with
Just kidding as I understand it Vista is supposed to be very photo friendly and it may have all of the capabilites you need.
Not sure of what to tell you other then I've had great luck with Adobe products. Usually a limited edtion version of Adobe Photoshop Elements, that often comes bundled with printers etc, is good enough for most photo editing techniques.
If you don't already have a copy of Photoshop Elements I would recommed getting a "30-day trial version" from adobe.com and start there.
Don't get overwhelmed by the capabilites of any photo editing software when you're first starting out as you really only need to have access to easy to use croping, brightness and contrast controls at first.
Keep in mind that 95% of photography happens in the camera when you take the picture and that is when you should pay the most attention to what you're taking a picture of and what settings your using. As one of my first photo instructers told me nearly 30 years ago was to always remember "you can't turn chicken poop into chicken soup."
For the last 2 and 1/2 year's I've been using Adobe Photoshop Creative Suite (CS2 I think) and find myself completely over my head with editing options most of the time so don't think you have to spend the $600 or $700 to get that progam (I think their up to CS4 now.)
I'm currently "trying out" a free "30-day trial" version of Adobe's Lightroom 2, as it is designed for photographers only where Creative Suite (CS) software is designed for web and graphic designers first and photographers second. I would not recommend using Lightroom 2 for your first photo editing software as it's taking me a little time to get used to but seems to be well thought out for professional photographers.
My best advice to start with is to use the K.I.S.S. method (Keep It Simple Stupid) and just concentrate on cropping, brightness and contrast then over time you'll start using other techniques to get the results that you want.
As far as dissing Windows' Vista from the begining of this post I'm actually getting ready to order my next computer with that operating system to give it's "built in" photo editing software a try.