unfortunately with a pump, you simply don't have the firepower of pretty much anybody else in paintball today, they're great if you're playing other people who are using pumps, i love them. But, if you want to be able to keep up with the pace of the game, a semi-auto marker is pretty much essential. There are some really good value semis around at the moment, the tippmann model 98 is a great example, really reliable and excellent value for money.
Kieran