paragon is (was) normally used when ppl wanted more than one version of windows on their machine (95 & 98)
windows 2000, XP and vista already have this option built in and will all work together on the same machine (simple menu option on startup)
with paragon ... you split your disk into partitions and install 1 os to each one - paragon then works by hiding the other partitions so your system can only see one at any time.
BUT with 2000/xp/vista
the first partition is the one that holds ALL the boot information for all the OSs - so if you hide it ... you can't doo not nuffin.
If he wants xp and vista or similar - just make two partitions and install - they sort themselves out
if it's XP and Linux - as far as I know (one of the linuxy bods will confirm) there is a prog with linux that does the job (wine?)
http://kb.paragon-software.com/paragon/include /templ/object2.jsp?catId=21458&objId=1027&stat Id=1114410&foLang=en
http://support.paragon-software.com/showthread .php?p=1331