It does, thanks!

I have just started mining for bitcoins using BitMinter and my stats are currently at 476 work units started on and 56 proofs of work accepted by the server. Is this normal due to the delay while the blocks are verified? I am running on a relatively slow GPU (4-5 Mhps); is it just that it starts work units that it doesn't finish? Would the number accepted compared to the number started go up if I had a faster rig?