Connection Speed General Question

I had a computer that was about 3 years old - it was a 233 mhz with 64mb of memory and had a 57k  modem.  I have a local ISP, and every time I dialed up, it always said it was connected at 115,200 bps.  I always wondered about that, as I had only a 57k modem, but I never asked anyone why it was showing 115,200.

I just bought a new computer, custom built to my specs.  It has a 1.0mhz AMD chip, 256mb of RAM and a 57k v.92 modem.  On my dial up, it "seems" faster, but the connect speed varies with each dial-up - I've been connected at 40,333; 45,333; 46,666; 50,333; but never higher.  Normally it is 46K.  One time it actually connected at only 28,800 ( I hung up and reconnected almost immediately).  I called tech support and asked them what was going on, and after discussion, the tech rep said that if I was connected at 45K +, that was "very fast".  My ISP is far from a fly-by-night company (they've been in business at least 6 or 7 years and offer DSL lines and have dial-ups from all across the country)

Here's my questions:

If I have a 57K modem, and my ISP has the latest and greatest equipment, shouldn't I expect to be connected all the time at 57K?

Is 45K+ "very fast" (knowing that it is not DSL), or was the tech guy just trying to blow me off?

What should I be expecting?

Thanks,

Carl