Why am i unable to find the LIB environment variable

I am a computer science student, I have installed visual studio 2008. Actually this was the first time i tried to run a program from visual studio command prompt.

When I tried compiling a program I got an warning saying

warning CS1668: Invalid search path 'C:\Program Files\\Microsoft

SDKs\Windows\v6.0A\lib' specified in 'LIB environment variable' -- 'The

system cannot find the path specified. '

and an error

error CS1619: Cannot create temporary file 'c:\Program Files (x86)\Microsoft

Visual Studio 9.0\VC\CSC600B.tmp' -- Access is denied.

I then tried to find the lib folder it was in C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\lib. But when i opened the environment variables window, there was no LIB variable. So i made a new LIB variable having the above path and again tried to compile the program, still there was no change in the warning.

My programs run properly using the IDE but i want to run it with the cmd prompt. Also how can i get rid of the error. Am using windows vista.

Please help .. thanks a lot.