I have the Brother PE700II and I am really enjoying it. Previously I had a combo machine (sewing/emb.) with just a 4"x4" hoop. Now I have the 5"x7" hoop and it really is a world of difference... so many more things you can do!
My particular machine has a USB port but you cannot connect a USB stick directly. You need to load the designs through the USB from your computer. I have a little netbook computer that I use exclusively for that purpose. Just figured I would mention that because it's the primary difference between the PE700II and the PE770 (which can read USB sticks). Of course, both machines can also read Brother embroidery cards.
My machine was purchased from Overstock.com, which still has both of the above machines. The PE700II runs about $500 and the PE770 around $600.