How would that work on not-exactly-broadband?
I live in very rural Oklahoma, on a wireless-tower connection which allows me to run City, but with noticeable lag, and sometimes unplayable lag. There is no prospect of increasing our bandwidth and there is no other option. We tried the Google Hangout the other day and the only way I could run it without disconnects was to turn all the cameras and video off.
Skype voice chat should work alright on that presuming 'not exactly broadband' is 'DSL' and not '28.8 modem and we have a bandwidth cap per month of the tune of 2GB of data' sort of thing. This is presuming you don't try to run screen share or virtual web camera or actual web camera, etc, and just use it for text and chat.
OpenRPG worked fine for me on Windows ME way back in the day, and I know personally it runs alright now on XP, Windows 7 64 Bit, Vista and Mac. I've had it work for a friend on Linux, briefly before said friend had to quit due to time constraints, if you use that as a virtual table top.
Personally I don't even run Skype for games, as I'm terminally shy and find I can't really RP very well 'in person', but I know that some folks absolutely need that personal 'I'm there with my voice' feeling.
I've never run the other program the guys are talking about so they'll have to help you with any technical issues that pop up with that, sorry.
I can help you find legal resources for whatever game you're looking into, if you want.
I've personally ran D&D 3.5, AD&D (though ages ago in middle school so I don't remember it so well), Shadowrun 4th/20th Anniversary Edition, Star Wars 2nd Revised/SAGA (WotC version, not the West End Games version), Hero System 6th, Mutants and Masterminds 3rd, new WoD (Vampire, Mage, Werewolf lines mostly only though), if you need help finding character sheets or resources or even just 'where to buy' for any of that.
If you're looking for a "City of Heroes" game the obvious choices I can think of are Hero System 6th and Mutants and Masterminds. I find the latter is easier to get into but is too heavily constrained by balance to allow for a large variety of strengths and weaknesses (you can build almost anything but a lot of it is mechanically similar), and the former is more robust but comes with a steeper learning curve (it's not actually so hard, it's just that the books themselves are very stupidly organized, I guess, in my point of view).