Actually from Windows XP you cannot do a straight upgrade, where it keeps all your settings and files. You would need to back everything up, reformat, install Win7, then reload your files onto your computer. You can only do a straight upgrade form Vista, and I believe it has to be 32bit to 32bit or 64bit to 64bit, you can't do 32bit to 64bit.
As for increasing speed, you most likely will not see a speed increase on your computer. Win7 while being rather nice and stable, does require more resources to run, and will most likely slow down your computer more.
You can check your computer out with this:http://funadvice.com/r/3l0b5qlb7h Windows 7 Upgrade Advisor. It will give you an idea of how well Win7 should run on you computer.
But if you just want to get more speed out of an older computer there are couple things you can try:
1) Backup, reformat, reinstall Windows XP. Sets you back to square one, but gets rid of all the little glitches and things that are slowing you down.
2) Just clean up you computer some. Get CCleaner, and run that both on cleaning mode and registry repair. Defrag you computer, I recomend getting something other than the Windows degragger. Run a full Virus/Maleware/Spyware scan, remove anything it finds. Techspot has a good guide for general Virus/Maleware/Spyware removal: http://funadvice.com/r/3jtk87u1gt
3) Reduce the number of programs that are actively running. Here is a good guide/list to services that XP usually runs, but you most likely aren't using: http://funadvice.com/r/15e64dkt9. Also XP will load a lot of start process that slow boot, and the computer. Better to load them when you need them. This site contains a list of common startup applications: http://funadvice.com/r/3l0b5qlbl3. Go to Start - Run - tyep in MSCONFIG. Go to the startup tab. Uncheck things you don't need. If you aren't sure what it does, check the referenced site or google it. You really only need your antivirus and firewall to start, and any other programs that won't function correctly if you load them after you start up windows. Might be a bit of trial and error, but with shutting off startup apps, you shouldn't be able to break anything.
Hope that helps
In my case I did a fresh install instead of an upgrade. I find Windows needs to be wiped and reinstalled every year or two anyway or it suffers creeping software rot. I backup my data then after my upgrade restore it.
The way I like to upgrade is to just buy a new hard disk. If you never overwrite you old hard disk than you have it as a backup if you find that you missed something or if you need to revert to your old OS for some reason. This should be the safest way to upgrade.
Win 7 is nice. It is definitely slower than XP but much faster than Vista. I had to buy a new USB serial port since my old one didn't have Win 7 drivers but other than that it has been uneventful.
Thank you for this input; I did wonder about an upgrade causing the computer to run slower. It's a four year old HP it runs slow enough as it is, I was wondering if the upgrade might allow it to run fresh.
It was never a set in stone decision though merely a notion alone. This helps me steer away from it though.
Possible, yes, safe...not entirely sure, as I don't have any experience with windows 7. What I've read though is that Windows 7 is far better than vista.
If you don't have to upgrade though, I'd strongly suggest waiting, as newer software will run slower on an older machine, until you can upgrade both at once.
Thanks for your answer, I have Windows 7 on my new laptop and love it but I don't want to kill my old one; it's been running with no problems four years. Speed and perhaps a few bugs from music downloading have been the only issues.
Thanks a lot, I will take these suggestions into consideration