I have never used an evaluation copy of Windows OS. So i am not certain on its install routine and uninstall. But being that it would be a evaluation, there is a good chance you will be able to revert back to the older windows installation. As the system would be designed to demo, trial the OS out for you, and i dont think it would be too popular if it destroyed - purposely, all the data on your system, but thats what i would think, but that might not be how Microsoft thinks.
I think you will have to buy a full version or upgrade version - if your qualify, once the trial period ends and you decide to go forth with XP.
I have run XP Pro on many machines, and for all the additions to the system, i did not see it as much of an improvement, those additions or "innovations" that Microsoft likes to tout on about are nothing that can not be fulfilled through 3rd party vendors. And usually you still are better off using a 3rd party app then those that are bundled with Windows.
Alot of the "innovations" done at Microsoft really amounts just to purchasing a company, 1 example is Hotmail, which was around for a while before MS snagged it up in '97. I believe alot of the newer DRM and audio codec technology comes from its purchase of Liquid Audio. Even the new Disk Defragmentor looks alot like Diskeepers defrag utility. And then there is Powerpoint, another "innovative" purchase. Some have even said that Word for Windows is derived from Xerox's Bravo. and if you want to really dig deep you then go to the GUI history of which MS innovated the idea from Apple who basically "innovated" the idea from Xerox PARC.....
If you end up using an alternative Web Browser, and an alternative File Manager and an alternative Firewall and alternative music player your removing alot of those "innovative" apps that MS has bundled into their system. If you want Remote Desktop Sharing, you can use VNC or even an older version of Net Meeting, as it has had that capabilites for a long time. Most of the newly visible additions to XP really were available in another version of Windows, but never made it to the forefront. XP uses Themes, which was available in Win95, XP uses Login and file security, available in NT 3.51, XP uses file/folder encryption which was in NT 4.0, XP uses ICS, which was in Win98se.
The only great change to the Windows system was when Windows morphed from Win 3.x to Win 95, and since then it has been stuck to that Win95 layout, sure XP added some new and rather annoying eye-candy, which is about all it is.
What version of Windows are you presently running? what hardware do you have? how old is our system? do you meet the requirements for XP? if you are using Win98se, and are familiar with it, you might be best just to stick with 98se. I dont see the justification for the cost spending to go to XP if your current system works and does well for you. If you just want to try the XP experience and have the money to burn, then go ahead. You might want to gather up all your devices - video cards, modem, printers, scanners... and make sure the developers have XP drivers for them, else you might have problems getting your older devices to work - not normally an issue though but worth checking into before finding out later you can't find drivers as a company has gone out of business or no longer supports their older hardware.
[*]Microsofts UPGRADE ADVISOR
http://www.microsoft.com/WINDOWSXP/pro/how...ing/advisor.asp[*]Xp Readiness test
http://www.pcpitstop.com/xpready/