svchost is pretty much what operates the background service(s) that run on your PC. It will more than likely use lots of CPU/Mem/HDD while the PC boots as that's when the services start.
Also vista does things like indexing files in the background which also runs as a service - more than likely as svchost.
Probably best thing to do is read-up on a guide on how to optimise the Vista service list (there's plenty on the net) and then decide for yourself what you do/dont need to run at startup.
Originally Posted by name='mighty_moll'
Its svchost causing all the problems by the looks of it. Thrashes the disk on startup for ages and looks at useless files like downloaded movies and mp3's. My HDD was at 100% usage by this process for over 15 mins.
At first i thought my new fans and CPU cooler were causing a similar noise to the HDD thrashing so i put my ear to the case for 5 mins lol But alas no - its the HDD as the constant activity light suggests...make the bad thing stop please.