If you were running Windows Update in the background, that would have really slowed down your system.
As I said before, IE8 is no longer being updated, so you should use Firefox or Chrome instead. That's why Gmail gives you that warning.
You mean a bootable AV CD? There are quite a few out there.
http://www.askvg.com/download-free-b...re-and-others/
It's your call on UBCD5. I would still make it, just to have it handy. I'm not sure what risks you mean. If you just run diags, it shouldn't be a problem.
I don't think you need to run SFC, but you'd need to have a slipstreamed XP SP3 CD. I'm not sure if that will work for an HP Recovery disc, though. You can read more about that, if you really want to run SFC.
http://www.bleepingcomputer.com/foru...-system-files/
http://www.updatexp.com/scannow-sfc.html
You should look at your current configuration first. Many times, you'd have 2 512MB sticks instead of 1 1024MB stick. This is especially true of dual channel configurations. So you'd probably have to buy a 2GB kit (2 1024MB sticks).