Most of the PCs I install XP on usually stick with SP2 since I have an XP Pro disc with SP2 slipstreamed, In my personal opinion this is the system spec guide I commonly see for XP and its service packs when it comes to best performance:
Windows XP RTM and Service Pack 1: Intel Pentium III (and AMD Athlon) at less than 1 GHz, or 64-256MB RAM
Windows XP Service Pack 2: Intel Pentium III or 4 (and AMD Athlon XP) between 1.1-2.4 GHz, or 320-512MB RAM
Windows XP Service Pack 3: Intel Pentium 4 (and AMD Athlon XP/64) at 2.4 GHz and above, or 512MB+ RAM
Windows XP Post-SP3 (all updates until 2014): No preferred CPU for now, but I hear it's better if you have more than 1.5GB of RAM
I have a few systems with a service pack other than SP2 for certain reasons, I have SP1 on my Dell Inspiron 8200 for nostalgia purposes, and I have SP3 on my Dell Latitude D600 and my Athlon 64 Gaming Rig so they're more compatible with modern applications, None of my XP systems go online these days so it doesn't really matter what SP I use.
Jorpho wrote:Some programs won't install unless it sees SP1 and doesn't acknowledge SP2 or SP3 so you have trick it to think you got SP1 installed.
Do you have a particular example in mind?
I remember StyleXP would refuse to install on SP3 because its installer has a limitation to disallow installation on anything other than SP2 due to it being made before SP3 came out.