Windows Vista PC users are experiencing difficulties with some broadband ISPs’ installation discs, with Virgin, Tiscali and Orange customers struggling to connect using Microsoft’s new operating system.

A spokesperson for Virgin Media told us: "This is currently the case with many ISPs. The situation with Virgin Media’s broadband service Vista compatibility isn’t a specific one”.

The company also confirmed that, in addition to the broadband installation discs not supporting Vista, only a limited number of its technical support staff are trained to assist customers with the problem. Virgin Media is working with Motive, which creates automation software, to produce Vista-compatible installation discs. Radial Point, provider of managed internet services to ISPs, is also developing Virgin Media’s security software to make it Vista-enabled.

Virgin Media was unable to comment on when the problems would be resolved but told us its technical support staff will be fully trained in aiding customers with Vista compatibility problems in the next few weeks.

But Virgin is not the only ISP to struggle with Vista; Tiscali users have also experienced problems with the new OS. The company advises that any important data should be backed up before attempting to connect.

T-Mobile, meanwhile, confirmed yesterday that its 3G cards for laptops aren't compatible with Vista yet. It has not set a date for compatibility , but insisted it was working on a solution.

Orange’s broadband service can be used with Vista, but some customers have been experiencing problems where their modem is recognised and installed but the installation process was not proceeding. The company says on its site that it's trying to sort out these problems and can still help to get customers connected. Orange also has dedicated pages to advise its customers with Vista.

Andrew Ferguson, editor of broadband analysis site, told us that as these are isolated incidents it is “hard to be sure if problems are Vista-based or normal broadband issues”.

"Those people who choose to install Vista will probably have less problems than those who buy a PC from the high street and are met by a confusing new PC with a new operating system and perhaps conflicting instructions designed for XP Home," he added.

Ferguson also confirmed that at least one person has been told by Talk Talk support it will be some months before their CD supports Vista. For Virgin Media cable customers, where the set-up CD fails to work, there are methods described to resolve this described on the forums.

Those that want to upgrade their operating system should also check with their ISP before to see if there are alternative connection methods to using installation discs.

Go here for PC Advisor's full review of Windows Vista.