The old HP I'm typing on isn't long for this world. When we replaced our computers at work, I was given one of our old ones which is in great shape because it was barely used - it's a Dell Optiplex GX260. The computer I'm replacing is an HP Pavillion a250n. Both operate XP. I can't seem to get online with the Dell. It was fine at the office but naturally, all the internet setting on the Dell would be configured for the office's network, ISP etc. I'm not all that computer savvy and can't figure out how to reconfigure it to work at home. My ISP at home is Comcast. The comcast modem is connected to my HP via an ethernet cable. When I run the Comcast internet setup software, I get a dialog box saying that it cannot establish connectivity and tells me the modem isn't connected properly. I know this isn't the case because I need only connect the ethernet cable back to the HP and I'm online in a flash and therefore, it can only be the various internet/connectivity settings in the Dell. I'm at a real loss trying to figure this out. Can anyone tell me how to change the settings they would have used at the office and configure this to get online at home so that the Comcast startup can read connectivity and get me on my way? Thanks much for the help everyone.

Thank you folks, will try both.

@Killerbug and ddp:

Thank You so much to both of you. You're instructions worked like a charm. I was curious about the disconnecting and reconnecting of the power cord and coax cable from the modem but I was later told that it works to "reset" the modem. Once again, thank you very much.