Besides not shutting your pirated version of Vista down when you fail to activate, Service Pack 1 will also bring a huge performance boost when you transfer both small and big files over your network. As you can see from the chart, throughput to and from Windows Home Server will jump to 3x, and throughput between Vista PCs will improve for small files but stay about the same for large files.
The difference comes from the way Microsoft dumped the XP-style buffering for network transfers, which resulted in a mismatch between Vista and XP (and a slow file transfer). The upside is that you'll be over to fling files over your home network much faster if you have one of those fancy WHS machines. However, if you run applications that use the Multimedia Class Scheduler, like Windows Media Player, it'll still kill network performance even with the new boost.