Hi rockreid !
Yes it %100 does include your Q9550 - so if/when you go to Windows 7, you will need to make this adjustment.
As riojazz noted it applies to all
Windows 7 X64 and X32 installations where the system is using more
than 2 physicial CPU's and/or more than 2 "logical" cores - ie: all Intel CPU's that are Quad-Core or higher.
PS: I assume it also applies to AMD quad-core cpu's but I dont use AMD for my DAW'a any more so I cant be certain, but my expectation would be that AMD quad-core would respond to core-parking exaclty the same as the Intel quad-cores.