If you decide to go PC, then wait until this summer/fall, when Windows 7 comes out. Most folks using the beta seem to like it, and it's supposed to address Vista's issues. I'd like to partition and install the beta on my laptop, but it's not going to happen as I'm nearly out of hard drive space.
From what I've heard, most netbooks running Vista are wayyyy slow, and preliminary indications are that Windows 7 will run much better. I've been wanting to get a netbook myself, but not one that's running Vista. My ultimate plan is to get a fairly cheap desktop to store/stream/transfer media files to TV/stereo/iPod and get a netbook for portable computing, writing, e-mail, internet, etc. My current laptop is a "desktop" replacement. It's not as powerful/big for storage as a cheaper desktop, and it's so large that it's really not that portable. I think getting two separate machines is ultimately going to help me get more out of their functions.
If you want a photo-editing software for Windows, try GIMP. It does a lot of what Photoshop does, and it's free.