I think this is more a question for a Windows help forums, but I'll try. Unless you have the top level (Ultimate) of Vista or Windows 7 installed you wont be able to install language packs, in which case the only thing you can do it to buy an operating system in English and format the drive and install a fresh copy of Windows.
Mcafee 2.0.181 indicates to me that there is a very small security program installed called McAfee Security Scan Plus which can be uninstalled in the normal way via Control Panel > Programs > Uninstall a Program (Add or Remove Programs in XP) - assuming you can at least navigate that far without the language foiling your efforts. McAfee Security Scan Plus is merely a tool to tell you what security protection you need and is not an antivirus or firewall, so it isn't protecting you at all and should be uninstalled. It often is an optional download with, for instance, any Adobe product, but there are others where, unless you uncheck the option, it will install automatically. It's merely a sales tool.