The 64-bit world can be scary and intimidating if you've never tackled it before.
One interesting tidbit about 64-bit support is that the PerfMon DLL is 32-bit. It's a simple limitation of WOW support that you need a 32-bit program to run and load the PerfMon DLL, when on a 64-bit platform, such as the X86 versions of PerfMon.exe. This isn't really much of a big deal, all things considered.
On the other hand, SQL Server 2005 fixes this for all platform combinations, i.e. 32-bit perf monitoring app against 64-bit SQL, 64-bit perf monitoring app against 32-bit SQL, since Microsoft is evidently installing both 32 and 64 bit versions of the counter DLL.