no tweaking as far as a base install goes. you should boot from the cdrom, remove the existing c: partition when beginning the setup program (when it asks you where to install windows to)- create a new partition, format it with ntfs, then just do a typical install. afterwards, you will want to enable the windows firewall, update to SP2 and all other security patches, then install a good antivirus.
just note that installing this way will make you lose any existing data or programs on the "oem" xp home load. you will probably not be able to reinstall the programs from the CDs that came with the system, as they usually only have a system restore disk, which would put xp home back the way it was with the programs already loaded (not true in all cases).
if it came with MS-Office, etc. - and you need to keep those software programs, then you MUST use the XP pro UPGRADE disk instead of full install. the upgrade will keep the currently loaded programs in place.
If losing the applications isnt a problem, proceed as described at the top.