When Vista rolled out, machines with XP didn't get a big discount. Besides you can get good deals on refurbs which most of the time are returns from folk that bought something and returned it shortly.
In other words, I don't expect you to see a firesale. Another reason is they are already clearing such out and the new machines will have a coupon for the Windows 8 update.
Since Windows 8 is being released on Oct. 26, I presume that computer sellers will want to unload their Windows 7 PCs ASAP before the new models optimized for Windows 8 (touch screen, etc.) are put on sale.
Any ideas regarding when and where the best sales might be for those Windows 7 machines?