|Sure but why? You'd spend more on the OS than is worth the effort. |
Just make a system that is fully supported in 64 bit or don't bother and make one for 32 bit. Very few programs still can even use more than 2G of memory.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10