From the Circuit City website [applies online and B&M]:
We want to make sure you’re completely satisfied with anything you buy from us. If you’re not completely satisfied with a Product, Circuit City will gladly exchange or refund your purchase within 30 days of the sale date—no hassles. Because of rapid changes in technology, the return period for digital cameras, camcorders, PCs and related products (monitors, printers, scanners) is 14 days.
For exchange or full refund of a Product, we need the order confirmation or record of purchase in our system. The Product must be in its original condition, including the box, packaging and all accessories. Opened software, music CDs, games and movies can only be exchanged for the same title.
Credits will only be issued to the credit card used for the original purchase. For merchandise purchased with a gift card as the sole payment method, we will refund the balance due to you back to a new gift card unless the balance is less than $5 or prohibited by law. See “Mail Refund” section below for refund information for merchandise returned via mail.
We reserve the right to limit the number of returns permitted.
So it looks like you're in the clear. Like someone said, they can look you up in the computer if you don't have your receipt. So they may or may not give you cash. You'll just hafta go down to the store and find out! Good luck.