Long time lurker here, but I just wanted to throw in my 2 cents on Microsoft Security Essentials: awesome product made even better by being free. I use it on all my home computers and have had absolutely no trouble with it at all. Yep, Microsoft actually gives away a very good product.
As for photo editing software, I've looked at several different ones (esp. since I can't justify the expense of Photoshop *and* still afford camera gear). I use Paintshop Pro -- you can often catch it on sale at various US shops for $20 or less. While the older versions were best (back before Corel bought them), the latest versions work pretty well and offer lots of bells and whistles for the price. While I haven't used it, there's a freeware program called Paint.Net (
http://www.getpaint.net/) that I have read good reviews about. Of course, the GIMP is one of the best open-source tools out there, IMO, but the learning curve is almost at the same level as Photoshop.