You might consider purchasing a firewire interface (usually has lower latency or delay and better quality than usb), like "presonus firebox" which has 4 inputs, where you can send the stereo outs from the MPC to a DAW like cubase le (which comes with it). Other than that, I'm not sure you can convert ".seq" files to .wav or .mp3, I've never tried. And if you want good quality, a firewire interface would do the trick if it's in your price range.
And also, if you want to get by without buying more gear, you can send your "stereo outs" back into the "ins" where you would sample, to sample your entire beat as a .wav file (if you have enough memory to do so). Hope this helps. Thanks.
