Looks like Newegg is having a sale on OEM versions of Windows 7, and they are offering an additional $20 off if you later upgrade to Windows 8. You won't receive an extra notification email of that extra $20 off until Windows 8 is available to the general public on Oct. 26th.
The promo code for Windows 7 Home Edition OEM is EMCNAJC22.
The code for Windows 7 Pro is EMCNAJC23.
Both of these are the 64 bit editions, with SP 1.
I don' t see how the extra $20 off for Windows 8 will be able to match the upgrade offer directly from Microsoft though. Its only $39.99 for the downloaded version.