My PS3 is connecting but XBox won't

Hello,

I've got this problem. Ever since i sent in my lap top to get fixed, and then returned, my XBox can no longer connect to XBox Live. I was always able to before i sent in my lap top. Now i have tried connecting it straight from my main computer and it still doesn't work, the weird thing is tho that my PS3 works perfectly fine on my main computer. What can i do? When i test my connection it never goes past the "network" stage and tells me it can not find my network hardware or whatever. I don't know what to do. Please help me.