Now that you've identified the base requirements, you're also going to need to know if all the hardware inside your current PC is also compatible with XP. To help you determine this, Microsoft developed the Upgrade Advisory Tool.

Get the tools

The Upgrade Advisory Tool is available for download here and is the exact same program Windows XP runs prior to installing itself. Basically, it just checks your current hardware configuration to see if it will support XP.

Caveats

The one caveat to the upgrade advisor is it's only going to check to see if your computer is ready for XP Pro. Why didn't Microsoft just call it the XP Pro Upgrade Advisory Tool?

If you download the upgrade tool, you'll be directed to find out if you're eligible for a discounted retail upgrade package. I'll save you from having to click another link and just tell you that if you're currently running 98 or Me, then you're eligible for a discounted upgrade to Windows XP Home Edition.

If you're currently running 98, Me, NT Workstation 4.0, Windows 2000 Pro, or Windows XP Home Edition, then you'll be eligible for a discounted upgrade to Windows XP Pro.