Unable to get on Google.com

I bought a Dell Inspiron E1405 laptop in June, 2006. Running Windows XP. It is running wirelessly through a Linksys WRT-300N router. I utilize AOL 9.0, IE7, and the latest version of Firefox Mozilla as my web browsers. Right from the start, I have been able to connect to Google on AOL, but unable to connect to Google on IE or Mozilla. Interestingly, once I am able to connect to Google on AOL, I am unable to connect to Gmail.com, their free web-based email account. (sidebar: I initially had Google Desktop on the laptop and removed it. I recently reinstalled it, and it did nothing to help me (Google Desktop reads my desktop only, it won't let me surf the web from there.) I have again uninstalled Google Desktop, but left their indexing on, just in case I want to reinstall it again in the future.) I have called Microsoft who tells me it's the way Dell configured my computer and they can't help me. I have called Linksys, even, and explained that I also have PC the router is plugged into the does work with Google in every way, including being able to access GMail. After talking to them for a while, they realized, as did I, that it's not a router problem at all (I realized that, but wanted to talk to them anyway.) When I spoke to everyone, they all indicated "it must be a either my proxy settings, or my ISP is blocking certain sites." I called my ISP--they do not block any sites. I checked my proxy settings and tried all different configurations (on IE, I did: Tools>>Internet Options>>Connections>>LAN settings, and then tried all different check boxes---nothing works. I have added Google.com to my Trusted Sites in IE, but as said,,,this isn't just an IE problem. I suspect there is something wrong with the laptop itself, its settings, but I just don't have the savvy to help myself. Its' probably a simple fix, but it's beyond my limited knowledge. Help!!!