WD Model Number Format for OEM and Distribution Channels:http://www.wdc.com/wdproducts/library/other/2579-001028.pdf
E = Mobile/WD Blue; WD Green; WD Black; WD Scorpio
P = Mobile Advanced Format/WD Blue; WD Green; WD Black;
T = SATA 3 Gb/s with 22-pin SATA connector (Mobile)
AISI, both drives should work OK. However the AF drive may need special attention (in Windows XP) to ensure that its partitions are aligned on 4KB boundaries, otherwise there would be a write performance hit.