Acquiring Network Address error

Ok So I live in a dormitory on campus and recently ran into a problem with connecting to the internet through the Ethernet cord in my room. Every time I opened up my browser I got this message that said something like virus quarantine. A virus was detected originating from your system please contact your system administrator. But the thing is I can connect wirelessly (I get a real low connection from a nearby wireless network)..and wherever else there's wireless internet. Ok so I ran spybot and Superantispyware(or whatever its called) and It showed some infections and adware and stuff. I quarantined them, and I noticed this trojan named trojan.dns(something like that). Now to make a long story short I rebooted my computer after quarantine the items but I can't get on the internet wirelessly or through LAN. It stays stuck on acquiring network address. I did a system restore and I could get on wirelessly but not through the LAN. I think it has something to do with that trojan.dns thing,because when i deleted everything but that I could still get on wirelessly but couldn't get on through the LAN(no acquiring network address). I deleted the trojan.dns and voila stuck on acquiring network address. I did a system restore back to where i can get on wirelessly but not through the LAN. I tried to do the ipconfig/renew thing but it didn't work. Can somebody please guide me to getting my LAN back. Thanks in advance....just to let you know if you post something within the next four hours I probably won't be able to respond because I'm not in my room right now(school work) but I will be withing the next 3 or so hours so I can get back to the ethernet cable and be able to test some fixes. Like I said before thanks and if my description wasn't good enough just tell me and I'll try to explain as best as I can.