"Reply from 192.168.1.5: Destination host unreachable."

Who's 1.5? Who's 1.3 for that same question. Also, if FB loads but not TMO, either TMO is fiddly (it is sometimes) or you have a DNS issue, rather than a connectivity issue. Or gateway, or routing.

Vitamid:
"I was able to connect from Windows by having the N900 terminal constantly ping my Windows box. I'm not sure what the root problem is exactly. "

How's the firewall? What are your connection settings? Do you do forwarding from router? What's your setup? And finally, if Windows doesn't do it, then it's not an N900 issue, it's a router issue.

My best guess is you let Windows on automatic and Linux on manual, and Windows has a bad config. Use ipconfig /all and compare settings. Seems like an iffy gateway or DNS setting. May be a lease problem, one IP is fixed and the other isn't, but the router keeps the lease, since it's the same MAC.

Either way. Use a 3G connection or a different (correctly configured) wifi before digging around OSs for issues. If it works fine in an open wifi or over GPRS/3G, you have a configuration issue with your network setup.