Belarc Advisor won't give your product key, it will give a Dell SLP key.
See information on my Windows Reinstallation Guide for more information which may be found in my signature. The product key should be underneith the battery.
Both Belarc Advisor & Produkey programs give me the correct WIN 7 PRO product key for my Inspiron 1525 laptop. Both programs also provide the correct product keys for Office 2010. I have run these programs on at least 10 other PCs with the same results.
ALWAYS download and install Belarc Advisor from the Official Site.
Hackers put up links to malware that claim to be the Legit product.