Swapping hard drives?

heres the story:

replaced the motherboard, cpu and ram in my desktop. came to use it and it wasnt recognising XP Pro on my HD. so i installed XP Home (only disc i could find) on my second HD to use my new setup.

so now i have the C: drive which contains XP Pro, which i am not using. and the D: drive with XP Home which the pc is running from.

My question is can i make my D: with XP Home the primary drive and wipe the old C: with XP Pro without screwing up the pc? and how would i go about it?

thanx for any help