Your setup is incomming internet into a High speed modem, then out your modem into your pc.
This is why we must find out what you have because you see some folks have a Modem, to a router to a pc or just a modem to a pc.
ok now the real question and will post this for other techs as to why you are having problems, my thought would have been a router but now we know you do not have one that eliminates the problem I was thinking.
Normally when ever you format a hard drive and and once the internet has been set up with your provider, you always get right back on line with no problems, but in your case you do have problems and now I do not know what to tell you at this point. Because here in the United States, once an account was setup you no longer have a need to set it back up again after a machine has been formatted or buying a new computer. Where you live I am not sure of how they operate.
Like you said when running XP you had no problems, but now you installed Windows 7 you got problems. Kinda making me think their was an install / setup was not done right but again I am a bit lost on this.
Watch for a responce for this post.
Edited by Jimbo1, 06 October 2010 - 11:42 AM.