Mine are in C:\VSTPlugins - specifically C:\VSTPlugins\32bit and C:\VSTPlugins\64bit for VSTs I install by hand, and in another subdirectory if a program is installing a bunch of associated plugins that may be either 32bit or 64bit - such as my C:\VSTPlugins\Sonar subdirectory.
 
Noel makes a good point about the potential problems regarding installing to places other than the defaults, but in practice the defaults aren't always a good choice because neither VSTs nor DAWs do a good job of following the rules for where data should be placed, sometimes throwing data in alongside the program as KPerry said above.
 
Other reasons I like having VSTs in a simple place like C:\VSTPlugins is to make it easy to back them up (although some will still have their auth data stored elsewhere unfortunately, as well as some (quite rightly) storing their samples in some other place) and to make it simple for other DAWs to access them (as I have REAPER and FLStudio on this machine too).

On Vista my profile was administrator and ran everything with administrator rights as default.

Is there an option in windows 7 to do the same? (so i dont need to right click and run as admin)

double post.. sorry

Elffin
On Vista my profile was administrator and ran everything with administrator rights as default.

Is there an option in windows 7 to do the same? (so i dont need to right click and run as admin)

Running from an administrator account is not the same thing as running an application using the "run as admin" command. That command elevates the privileges of the application itself. Win7 allows you to run an account as an "administrator". If you're the only account it'll be an administrator by default, partly because if there was no administrator account it would be impossible to configure the system-wide settings at all. You can also switch off UAC completely but I wouldn't recomend it.

The settings are in the Windows control panel/users application.