Dual installation

I'm considering leapfrogging from XP to Windows 7 (wasn't impressed with Vista) and therefore have downloaded the trial version. So far I like it but I've got a problem. I still wanted to keep XP and didn't want the two systems to know anything at all about each other, so I used Gdisk to hide my XP partition whilst I installed Windows 7 to another partition. Then I explored WIn 7 a few days. After this I reversed the hidden and active partitions, installed a fresh XP (which I had planned to do anyway) and everything seemed to be working fine. Today I changed once again with GDisk so the Win 7 partition again was active and I could play some more with it. To my very great surprise I discovered a whole bunch of programs were available which I hadn't installed, but which, on closer inspection, turned out to be the programs I had installed on my original XP. (Some of these weren't functioning properly which is why I'd decided to install a new XP also.) On the other hand my new XP is now no longer available; when I again use GDisk to revert to partition 1 the XP startup starts, and I can use the recovery console but when it gets to the windows logo with the small blue cubes, the process stops and the machine restarts. Apparently Win 7 (like Vista?) does something with the boot sector which XP doesn't like. Can I get round this problem? Linux boot loader perhaps? Tried fixmbr bootcfg etc to no avail. Win 7 is good, but I still need XP for a while until I've mastered 7. Thanks for any advice..