My computer won't connect to the internet!

I purchased an Alienware m14x last June. I also got the warranty that lasts a year, which guarantees that Dell would provide aid if my computer isn't working right. For the first 7 or so months my computer was working perfectly, after 7 months my computer started freezing frequently... But, recently my computer started doing this thing where it'll look like it's connecting to the internet, it will...for a millisecond then proceed to try reconnecting.It keeps doing this over and over again. I have wiped my computer three times now, wiping it did fix the problem...temporarily obviously.  I called Dell and spoke to them for about an hour and they "realized" it's most likely my wireless card since my drivers were up to date and they couldn't find a virus. Dell managed to get someone to put in a wireless card for me a week or so ago, now my computers is doing the same thing where my computer will disconnect...reconnect...disconnect. Please help? I don't know what to do, I don't care if I'll "lose" information...