i've got a blue next one with uses the latest chipset can't remember what it is, but its meant to be better than the Sirfstar3 chipset.
Its about 1/3 of the size of the N73, but is very good.
This is the 2nd one i bought for £30 after the first one jumped of my bike at 80mph.
I've got the keyring GPS which you can find if you search sensibly, its done me very well, locks on great, is sirfstarIII and one of the smallest there is around. Funny enough it just sits on my keyring looking like a key fob...