The E-Value codes available for the $750 off coupon are as follows: 11111-i600MA2, 11111-i700MA2, 11111-i6000A5, 11111-i6000A6, 11111-i6000A7 or 11111-i9300A2. Notice the discrepancy between the 700M E-Value codes (MA2 v S0). Also notice the last line above - "these special configurations are not combinable with instant dollars off or percentage off promotions".
"Offer is available on these E-value codes or order codes containing the following sequences only: i1200S0, D80606, D80608C, i2200S0, i6000S0, i600mS0, i700mS0, i9300S0, iXPS2S0, iX1S0, D24F1, D30CF1, D30PF1, D47F1, D47CF1, D84F1, D91F1 and DXPS5F1.
Valid for new U.S. purchases through Dell Home Systems. This offer is only combinable with select other offers. These special configurations are not combinable with instant dollars off or percentage off promotions."
In short, you may have qualified for the coupon, but your rebate will likely be denied. You'll want to check with Dell to make certain the machine you purchased will be applicable for the rebate.
For those interested, the link to the rebate, and the link to the coupon information.