I'd buy the T61 (mine is currently in Kentucky and should be here in two days...I love UPS tracking).They're a great price right now at lenovo.com and you can insist that they lower the price even more (I had a lot of success doing this).
I'd agree with going to PC route. I know they've made strides, but a lot of campuses aren't really Apple friendly. And even if yours is, most businesses use PCS (anyone notice a lot of places buy Dell? Our courthouse only buys those). I've heard a lot of good things about Macs, but I like to stick with what everyone else is using so it's more comaptable for everyone involved.