We have bought Macs for the last 2 years on tax free weekend in NC. We haven't had any problems getting our free ipod (8G) and even got the free wireless printer last year, too. They have been very quick to send the checks after you complete the online rebate.
I had to show my card from the DNPE at the store the first year, but when I purchased online the 2nd year, they took my word for it. The educator discount was even better than my husband's work discount. :0)
I have a 21" screen and find it sufficient. I will say that my husband has used a "pc" screen for his macbook pro and the graphics are just NOT the same.
HTH