Well, I was going to do it, but we figured out that 64-bit wasn't worth the trouble yet. It's not that much worth it until standard PCs ship with well over 4G RAM.
Ron Kuper sez 'no'... http://www.cakewalk.com/x64/whitepaper.asp
" the CPU has twice the general purpose registers and twice the floating point unit (FPU) registers, compared to x86 processors. And each general purpose register is also twice as wide, 64 bits instead of 32 bits."
"For a specific example of why this matters, consider a digital equalizer. The math involved in computing equalization usually involves a processing element known as a "biquad". A biquad is a small code fragment that manipulates 8 numeric values in a series of additions and multiplications. The x86 floating point unit has a total of 8 registers, so even something as simple as 1 biquad will use up all of its registers. "
Apparently there are other advantages to the 64-bit mode, but I've not witnessed any difference with the programs that I use.
And then many programs' RAM usage might nearly double, especially programs that use lots of pointers
it is almost 2x, from what i recall, but having finally replaced the last Celeron here with a Sempron64, i can't double check..