Visual Studio .net

Question

I installed Visual Studio.Net from a DVD that comes with Microsoft MCSD/MCAD exam books. Now every time I start Visual studio, it gives me a message that Visual studio English version will expire 2 days or 3 days.... Is there anyway that I can stop the installed Visual studio from expiring. I don't want to go thru all the uninstalling and installing new visual studio process again. Please help ! Thank you. C_sharpkid1