28sweep, IL2 online is free and fun.
Online play may be entered through the Ubisoft software and they have 2 servers up, one for easy dogfight with all planes and one that is full real and limited to 1941 planes.
There is also a coop meeting area where you can join up to 15 others in missions hosted by a player on his computer.
A better online option is to go to
http://hyperfighter.jinak.cz and d/l the Hyperlobby client.
There are usually at least twice the players in Hyperlobby and the level of play seems a bit higher.
I do not understand why you cannot log into the Ubi servers, did you install Ubi.com from the IL2 disc?
If so, delete it and get the version directly off the Ubisoft main site and it should work.
Better yet, delete it and go get Hyperlobby, more dogfight ops and better coops although waiting for a coop mission to fill can take a few minutes.
I do not go into dogfights much but I hear they can get laggy, probably partly due to the fact that many there have custom skins which must be updated as they appear and the detail of the sim is very demanding for online play, not such an issue in AH or the other one with simpler detail.
Put 32 planes, gvs, A A bursts, bombs exploding and planes going down in flames into an extremely detailed terrain and something has to give, right?
It is usually the computer.
Coops are limited to 16 players but many missions have a lot of AI planes involved so if you have less than a 1 Gig processor and 512 RAM and a GF2 or better be prepared to slow down in the middle of the action and even with those specs things can get messy.
For a boxed sim the online aspect is the best I have seen but my experience is limited to WWII Air sims so there may be a better one out there somewhere.
It ain't AH Online but it is the next best thing.
It is the only thing keeping me away from AH.