Need advice on computer for teenager

Complaining that the computer is too slow. Its a Asus P5wd2 Pentium D805 1gb WinXP ram and some old 40gb harddrive.

Don't really want to snoop around on it. Thinking a new 7200 rpm hard drive and a fresh copy of win7 would make this last a few more years? Its not used for gaming.

Or I could use the excuse to upgrade my Q9650 system to a Sandy bridge and turn my system over to her.

So I guess I need to know how the performance of a PentiumD 1GB of ram is with windows 7 as far as the internet, email, and itunes ?

Hmm.. I'd be surprised if it ran Windows 7 to be honest. You can download this tool and run it on the PC you have in question. It will give you the answer.
Free Download PC Upgrade Advisor Windows 7 Hardware Programs Issues

Maybe you can give the HDD a format and give XP a fresh install. That should get them by if that criteria is all they are planning to do.

If you install Windows 7 and leave the product code blank, you can run it for 30 days as a trial. That way you can test it out without spending any money on a new license. If you're happy with the performance then you can go out and buy another copy. You can run the upgrade adviser from XP, and I would definitely do that first.
Another option would be to buy a bare bones system for her. You should be able to find one that includes, a case with power supply, RAM, processor with heat sink fan, motherboard and hard drive. Some assembly required but you'd get the tower and all the internals required to setup a new system except the OS. You just reuse your current monitor, keyboard, mouse, speakers etc. I know getting yourself a new PC sounds good but if you want to save a few bucks this is one way to do it.

I'd go for a windows XP install, its a bit (well a lot) too old to run Windows 7 well. If you want to upgrade to Win7 then your second idea sounds ideal!

pparks1 - yeah it could run windows 7 but given the choice I wouldn't install it on that spec computer - especially one that I wouldn't be maintaining and is going to a teenager who may not know what they are doing with it?