For a step up from GMud, which I used myself for some time, I would have two suggestions since I found the configuration of Monkeyterm quite awkward to work out... mostly because I couldn't be bothered to learn it when I can use other clients which have the options more immediately apparent.
MushClient can work quite well, its one major limit being it can only play one sound at once without tweaking. It is however free and is available from www.mushclient.com, and the plugins from www.randylaptop.com are highly recommended. I actually added this to the game list on the main ag.net site so you can also look there for more precise links for the randylaptop scripts.
Easier to use right away is the new VIP Mud from GMA at www.gmagames.com, with not just multiple sounds support but the ability to play them in stereo. It will work straight away with several speech systems, or sapi built into windows if you don't have one of the ones it directly supports. It isn't quite as flexible but is a little more user friendly, though after the first 30 days expire you can only use it for 2 hours at a time unless you pay for it or use it on Valhalla mud.
I would really, really not recommend anyone to use telnet even an experienced mudder. Even GMud is more advanced than that, and I found a lot easier to handle.
Hope that helps.
cx2
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To live by honour and to honour life, these are our greatest strengths and our best hopes.