Home internet connection not working

Hi everyone. I've got what seems to me to be a pretty strange problem. I use a hard wired ethernet connection both at home and at work. A few days ago my connection at home stopped working, and I presumed it was trouble with my home connection because when I went to work and plugged in there my internet works fine. Tonight though, I decided to do some investigating and found some weirdness. If I plug my wire at home into my xbox360 it works fine. If I boot my computer up into Ubuntu, and plug the wire into my computer, it works fine (in fact I'm doing that right now), but when I boot into Windows and plug the wire in it doesn't work. It seems to recognize that I'm connected to a network, but doesn't grant me internet access. Seriously, I didn't monkey with any settings at all. I took a nap Saturday afternoon and it was working fine, I work up and it wasn't. I'll try to supply any information you guys might inquire about because I REALLY hope you can help. I'm stumped.

Okay, I'm a bit of a noob when it comes to some of the finer details of Windows life because I've always had pretty much flawless luck with my computers. The last system restore point appears to be 1/7/2011 when Windows self-applied a "critical" update. I'm guessing this update is the source of my problem (which would put the timing of the problem after I got home Friday night and woke up Saturday morning). Having never done a system restore, I'm a little worried that I may lose some of the work I've done since then. Is that gonna be an issue? From looking around, it seems as though it shouldn't be, but you never know.

Also, with regards to flushing my DNS cache, would that trouble explain my internet access working in one place, but not another?

Thanks for your help, guys, I really appreciate it.

You could try checking the "Internet Protocol" settings for your home network connection. I suggest this as you said it works OK at work which uses a different network connection and the same is true when you boot up into Ubuntu which uses its own settings and not those in windows.