Many things are better in 7 than in XP...
• Aerosnap (can drag a window to the far left or right of the screen and it fills half a screen) - very useful!
• Internet Explorer 9 much better than Internet Explorer 8.
• Multiple monitor settings; Windows and P switch monitor settings fast (Although Actual Windows Manager helps both out alot).
• Increased security - UAC, Firewall.
• Taskbar/looks - pinning items.
• Drivers alot of things work straight out the box/Windows Update is far superior downloading/updating drivers.
• Support in XP ends in 2013. However now things are becoming unsupported in Windows XP. Internet Explorer 9, Windows Live Mesh are excellent Microsoft Services which you may use for Free with Vista/7 and are unavailable for XP.
• Shortcut keys, Windows and P, Windows and a number (loads the first 9 items pinned on the toolbar).
• MSPaint is much better. Snipping Tool, Sticky Notes.
• Library organisation is much better, folder layout etc. (Alt and ↑ arrow key) goes to parent folder.
• In general just alot more stable than XP (if done with a clean install) and runs alot faster if you have a decent computer with 4 GB of RAM or superior.
I am a fan of Windows 7 actually I like it alot more than XP. Vista with SP2 (clean install) is almost identical to 7 (now). Taskbar pinning and aerosnap aren't there which I keep forgetting when I am on a Vista PC. Also it tends to demand more RAM. Performance of 7 is slightly better than Vista (for me). Many people experienced significant problems with Vista.
If you add Office 2010/Windows 7 combination vs Office 2003/Windows XP then there are alot more advantages.