Problem with McAfee SecurityCenter while trying to update Vista to Win7

Hello everyone!

I have a big problem while trying to update Vista to Windows7 and hope someone is able to give me some advice:

I started the Upgrade Assistant (CD1 of the two I received from Dell), which made some tests first and told me I have to uninstall my WLAN Card first - what I did (so now I don't have internet on my laptop anymore...). Afterwards it said it has to remove some programms temporarily and is going to reinstall them after the upgrade, like a video chat programm and McAfee SecurityCenter. Everything could be removed properly except McAfee. It consists of several subprogrammes like Antivirus, parental control and so on, which all could be removed properly, but when the last step - the deinstallation of McAfee SecurityCenter itself - starts, my laptop freezes and nothing works anymore.

I also tried to uninstall McAfee via system control, but that caused the same crash. The update programme won't let me start the Win7-update as long as I have McAfee running on my laptop (which was by the way already pre-installed by Dell and bought together with the laptop), plus I do not even have an Internet connection anymore as it just deinstalled my WLAN card....

I would be very very grateful if anyone could help me with that problem how to get McAfee uninstalled without system-freezing and Win7 installed properly!

Thank you very much in advance!!!