Agreed... the 4-pipe 6200 is no faster then the Ti4600 he already has. Remember, the 6200 is the cheapest, budget, non-gaming card out of the entire GeForce-6 lineup, while the Ti4600 was a top-end GeForce4 designed for gaming.
You'll be pissing your money into the wind if you get a 6200 to replace a Ti4600... the only differance is that the 6200 supports DX9 features and SM3.0, but of course, the card is so slow, any attempt to use those features would turn a game into a slide-show... remember, the 6200 was NEVER designed to be a gaming card. It's a low-cost "stick this in my office-computer" kind of card.
Crypt33, I'd rethink your entire gift purchase here. You either need to cough-up some dough and get him a better card, or (if you have a DEFINATE budget-cap), you'll need to consider a USED good card from E-Bay, or just dump the whole idea of getting him a video card and get him something else all-together.
If you value your friendship (and it sounds like you do), don't tick him off by having him swap out a high-end GF4 for a bottom of the pile GF6 which will be a lateral move at best in gaming on his PC.