I was running Windows XP Pro x64 with SP2. Made a new partition, installed Windows 7 on new partition. On boot, I could pick Windows 7, or older Windows OS (XP Pro x64 SP2, basically Server 2003 SP2).

While these tips will help, your main goal should figuring out how to move away from Windows XP. If it is simply a matter of replacing a critical application, work out the cost and build that into ...