Firstly, you can see what problems you are likely to face, by downloading and running the Windows 7 Upgrade Advisor from:
http://www.computerac...ndows-upgrade-advisor
I did download it and it confirmed my suspicions that it was better to stay with XP until I NEED a new PC. Why?
Well, it gave me a considerable list of things that I use which either will not work with W7 or will need me to go to other manufacturer's sites and upload drivers or replacement software. Many of the things on the list were things that I did not have a clue what they were, so how will I know if it is going to be a disaster or not?
Even worse, if you are running XP or earlier versions, you have to do what is called a "clean boot". This means that you must copy all your files to a CD, DVD or Memory stick, load Windows 7, which will clean your hard drive, then re-install all your software from the original disks and then reload your files. If you run into problems, it is almost impossible to get back to your original set up, unless you saved a mirror copy of your hard drive before you "upgraded", and not many of us have the know-how to do that unaided.