That's not too bad, right? Definitely enough to support a better card. If you want to enjoy SH4 properly (or should I say visually), IMO a graphics upgrade is in order.
If you don't want to upgrade just for SH4, or don't have the money, stick with SH3. A lot of people feel that it is more immersive anyway. Biggest bonus from SH4 is (arguably) the updated graphics.
