The only reason that he won't be able to download anything or use the internet is:
1. He have to configure the
wap set up himself, the phones is unlocked so it have no
wap or
gprs set up.
2. He is currently using pre-paid, as far as I understand pre-paid
sim card are for the use of making phone calls only. If he have any doubt all he have to do is call t-mobile service center and asked for the
sim to be open for the internet and
mms.
I had set up quite a few of these phone for T-mobile and worked.