Honestly, I use a leaked corporate XP Pro key to install (32 or 64 bit). Haven't used Home edition.True if you do enough installs to make a slipstream version up. The problem I have with XP is that you seem to have to have the exact version/service pack to use the license key.
After install I use keyfinder to change the license key to the legit one... Service Pack is irrelevant (unless using a key that got blacklisted).
After updating last spring (AHCI, half a dozen new network drivers, etc.) I haven't changed the boot CD. Used it a dozen times or so.
nLite does a very good job. The first time it takes a while. Every other update takes less time than burning the final CD.