Lenny,
If you have a DVD burning drive in your computer, why not download an iso file for a live Linux disc. There are several to choose from, are free and after you have burnt the disc image file to create a bootable disc, when you want to undertake internet activity you just boot your computer from the live disc. You then would not be using XP for internet activity so could disable network connections within XP.
If you have plenty of room on your HDD, a more complicated alternative is to set up a dual boot system so that you have both XP and a Linux operating system installed on your computer - when you boot the system, you can select which operating system you wish to run. Linux is inherently safer than Windows when online.
The beauty of the live disc option is that you can try it but you are not comitted - if you don't like it, you can try another. The minor downside of a Linux live disc is that apart from Puppy Linux versions, is that the default language and keyboard settings are for US. You can change them to say UK for a session but they will revert to default next time. Puppy is clever in that it can allow you to save settings as it works in a rather different way - in fact if you install a Puppy distribution on a DVD-RW disc and choose to create a special folder on your HDD, it becomes a very flexible live disc system.
