I installed SP1 successfully on two Vista machines. One was a Vista Biz 32-bit, and the other 64-bit. In both cases everything went fine.
However, in both cases MSN Messenger was killed and had to be re-installed. Also, on the 64-bit machine I had to reinstall the Auzentech Prelude sound card drives because I got no sound once SP1 settled in.
Both of these machines are still running problem-free. The 32-bit one is a laptop which supposedly should get better battery life. It does boot up a little faster since it's an older machine.
But on my main machine with 64-bit Vista Biz I see no difference. It was smooth as butter already even before SP1.
__________________ Main: Intel 2600K @ 4.8GHz | Gigabyte P67A-UD7-B3 | 16GB Corsair DDR3-2000 | 2 x 240GB Corsair Force 3 in RAID1 | 2 x 4TB Hitachi 7K4000 | 3 x 2TB WD Caviar Black | 3WARE 9650SE | Antec 1200 | Seasonic XP-860 Platinum | 2GB GTX 670 | 2 x 27" Asus VE278Q | Auzentech Prelude | Win7 Pro 64-bit |