How to delete windows 7 beta trial? -

i downloaded windows 7 and now my computer is facing lot of problems and i want to delete.Because i downloaded windows 7 my windows vista got deleted and now i want back my windows vista.i have the product key for windows vista.Can someone please help me delete windows 7 and download windows vista again

If you have the restore disks that came with your computer, you can use them to restore your computer to the exact way it was when you purchased it including Vista. WARNING: This process will delete any programs and files you have on your computer that you ve added since purchase.