I'd use Pro. Microsoft crippled some features in Home (like joining an Active Directory Domain) to keep businesses from using it. While you may never need the crippled features, I'd rather have it all then find out later I did.
Get Pro, Home only supports 1 CPU.
If I buy an OEM copy of XP SP3 will I be able to install it under parallels without any problems?
...Home supports multiple cores just fine...
Nope, it does not. It runs but uses only one core.