Oh... well, I'm really not the most neutral person to ask, and probably Nova will have an entirely different opinion. But from what I have heard, bad and/or fluctuating pings are no rare and isolated cases. Being unable to connect to Steam etc., well... I won't comment this, because I solved the Steam-related problems I had in a very... ummm... *cough* particular way.
I think I remember that someone said the ping problem was really a Steam-related one - if this is correct, then the solution will be to wait for the next Steam update and maybe pray a little, if you're religious.
If there is anything else you can do (assuming that your netsettings are ok), I don't know about it, sorry.
However, I'm sure Nova will see this thread soon, and since he's probably the guy with the best Steam knowledge here, he might have more information for you. Good luck anyway...