|Probably, but 40GB is pretty small. With the price of an enclosure half what you could buy a much larger external drive/ enclosure, why not go for a larger unit. Look at the link below for some examples. Newegg.com is an excellent online retailer that you can trust.|
There are basically two catagories of USB external drives. 2.5", which are more portable and 3.5" which require an 120VAC power supply but are more dependable. If you need the portability then get the 2.5", otherwise get the 3.5".
In the advanced settings at newegg.com you can filter according to specs.