I would go with an Wacom Intuos 3, they are more sensitive than the consumer grade graphire and bamboo and since you mention this is for an architectural student, the higher grade pro level ones may be more useful.
You can get a good Wacom Intuos 3 6x8 for $210 on Adorama, refurbished though.
UPTZ630 Wacom Refubished Intuos3 USB 6"x 8" Graphics Tablet with Pentools, for PC & Mac
You can get a good Wacom Intuos 3 6x8 for $210 on Adorama, refurbished though.
UPTZ630 Wacom Refubished Intuos3 USB 6"x 8" Graphics Tablet with Pentools, for PC & Mac