If you have a MSDN or TechNet+ subcription then you can download and install Windows Vista SP1. The installation process is simple (run the correct .exe for you Vista language and binaries) and it will install and reboot. During the first reboot it will install in 3 stages (sometimes with reboots) and when finished it will present the standard logon screen.
I haven't had any problems installing the update (have done it on 3 PC's) and have noticed that wireless networking and some file operations (copying) is working better after the patch.
Find the MSDN download here (you must logon to MSDN):
Link to file on MSDN