Slower = Faster? Here's why: The modem business is very competitive, and the first thing a typical user will consider in evaluating a modem is how fast it indicates it has connected. With the advent of 56k modems, the CONNECT speed reported gives less than 1/2 the picture: first, only the downstream rate is indicated, and second, the modem may not be able to sustain the speed at which it connected.
If the modem is unable to decode the data at the connect speed, the modem will either retrain or do a rate-renegotiation. Both of these events interrupt all data flow - in the case of a retrain, the interruption can be 20 seconds or more of nothing!
Because most users do little more than compare connect speeds of modems, manufacturers have an incentive to be too aggressive with connect speed so you think your modem is faster.
If your modem is connecting at a rate below 40K bps, I strongly urge you to check your throughput with 56k disabled altogether. You may be surprised to find that your modem (a) connects to your ISP faster; and (b) performs better.
If your modem is connecting at a rate of 40k bps or above, but your throughput doesn't match, or if you experience disconnects or unreliable connections, I recommend you try limiting your speed connection to a lower rate.
After you've tested the various options with your modem and present modem driver, I suggest you check to see if an updated driver available, and then re-check and compare the performance.