SP1 includes the 48 bit LBA registry entry, but it may not be enabled when you look after install if you use third party partitioner.
As was said, you can even have a 1 terabyte dr, but if your partitions are under 137 it doesnt matter - you dont even need SP1
However, to be safe, since we are dealing with "real" and "phoney" MB here, its best to keep all partition 125 or less, so one doesn even have to stop and think about actual digital sizes.