Windows 7 Pro 64-bit : OEM install over retail while preserving data?

I recently installed a retail version of Windows 7 Pro 64-bit onto my PC with the intent of using the 30 day trial period then activating it with an OEM licence key if all of my software and drivers worked okay under the 64-bit OS.

I've now been lead to understand that it is NOT possible to activate the retail installation with an OEM key, so apparently my only viable option is to buy a retail product, which of course costs a lot more than the OEM version (and I'm not exactly rolling in money so I need to take the cheapest route).

I would naturally prefer to purchase the OEM version.

Would it be possible to buy the OEM disc and product key, then "re-install" over my existing retail installation without losing any of my current configuration?

I have quite literally spent DAYS configuring this retail (trial) installation and now that it all works I don't want to have to re-install everything from scratch if I go the OEM route.

Surely it's possible to "update/refresh" the trial Retail installation with the OEM disc so that I can then use a purchased OEM key?

Thanks

Thanks for the reply.

That's a pain - not unexpected considering it's Microsoft, but still a pain!

Don't you think it seem ridiculous that it's not possible?

OEM versions aren't legal for non professional system builders?

Really? I wasn't aware of that.

They're openly sold everywhere ...... Amazon, Ebay, plus loads of very reputable PC hardware retail outlets, etc.

RolandJS said:

I hope you have current backups of all your data. A reinstall of your programs is work enough; don't want you to have to recreate all your data.

No worries there. :)

Did you try activating with your OEM license ?
As long as the version of the key such as Win 7 Professional matches the version you installed the key should work as far as I know.

Can i ask, where did you get a Retail disc without a license key ?