I assume you mean you now have a Raid pair containing a copy of vista and the old disc with a copy of XP on it.?
When you say deleted the partition did you uninstall vista first?
What you should have done is uninstalled vista to make XP the only operating system.
Removed the boot manager so the PC automatically booted into XP by default.
Removed the Vista partition or merged it with the XP one.
Done a disc clean up.
Now install the Raid pair and install Vista on the pair as desired.
Re-instate the boot manager.
XP does not have native support for raid. but you can buy third party apps that will make it happen. The MS knowledge base also has some useful stuff.
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