Don't forget that there are two StartUp folders in Win2k and XP.
Right click on start and "Explorer All Users" and you'll find one Startup folder - common to all users thatlogin to your computer (including you if you are the only one), there is also another option on Start Right Click just saying Explore. This opens you personal user based Program folder and in there you'll find another Startup folder.
If you want it to "disappear" you will need to hide both. Not sure if this'll work though.
There are good reasons for keeping it visible though - esp. if you install and unistall bits and bobs a lot in that you can see what installers have added to these folders. Often these are links that load tray icons, and if you want to get shut of them you just need to remove the item from the startup folder(s).
Most of the startup items that you shouldn't remove are hidden away in the registry.
By far the baset way to deal with these management issues is by using StartUp CPL at http://www.mlin.net/StartupCPL.shtml
which allows you to see pretty much everyth application that loads things at startup and allows you to remove them (whilst keeping a backup in case things go wrong and you need to put it back)