How to know if My product key is a valid key

Question

I have read some threads about people buying Windows 7 product keys on ebay and they are prob no good. I bought 2 product keys for Windows Ultimate 7, but didn't buy them off ebay. But how can I find out if my keys are good keys? After I bought the keys I was given a link to what I think was msdn site to choose my language, and my product That I bought the keys for and I used easymule to download the Windows 7 Ultimate 32 bit iso.
Before I go through the trouble of formatting my drive and installing Windows Ultimate 7 I was wondering how to tell if these keys are valid and make Windows 7 Ultimate a good copy and get updates. But I dont want to post the keys here if they are good because I paid for them to use and dont want someone to use them before I could activate them.
Bryant

Answer 1

I think there are a number of companies selling key with links to a Microsoft download site.
We were scammed once, so I developed a few guidelines to prevent another scam:
Before you buy ask:
Is the site you are purchasing from a Microsoft Partner? They will be listed with Microsoft.
Are they based in the US (or the country you are purchasing in)?
Do they have a number you can contact?
Do they pick up the phone quickly?
Do they have an acceptable degree of knowledge about the product?
How many bad reviews do they have? (it is easy to create fake good reviews, but harder to erase bad ones.)
After you buy:
Open chat with Microsoft to verify that the key is what you were told it was.
While phone calls may take a long time, the chat que is usually a minute or less.
If it is valid, go ahead and use the key with your product as soon as possible.
At the time I purchased Office 2010 Professional, legitimate single copy retail prices ranged from $119 to over $500 on the internet.  So, it is still
worth shopping around.  The above guidelines should help (had I followed them the first time, I would have easily avoided the scam and still have found an excellent price).
Also, if you are purchasing multiple products, you might purchase just one at first, to verify the company is legit, before you risk a lot of money.