Re: Older computer & service packs
You need a LOT of updates if it is still on XP Service Pack 1. I would advise not doing any general web surfing on this PC until you get it brought up to date.
Basically, Microsoft frequently issues minor patches, usually a few each month. Every few years, they release a "Service Pack" (SP), which is a roll up of a BUNCH of minor patches, along with a few new features. (For instance, XP SP 2 introduced the Windows Firewall). SP3 is the current (and will be the last) service pack for Windows XP. However, there have been MANY (100+) patches issued since SP3, so the PC in question has a way to go.
Launching "Windows Updates" will start the process to bring the PC up to date...You'll be prompted to install a BUNCH of updates, so expect several reboots. Hope you have a fast Internet connection!
To start the process, launch Internet Explorer, then go to Tools-->Windows Updates.
You'll probably have 2-3 small updates that need to be applied (probably one at a time). After each one, just tell Windows Updates to check for updates again. Eventually, it will get to the Service Pack 3 update. This will be a BIG download. Once it applies, you'll be asked to turn on Automatic Updates. Say YES. There's still 100+ to go, but it should just be 2-3 more reboots. Somewhere along the way, the upgrade to Internet Explorer 8 should be applied.