Businesses should expect a migration to Microsoft's Windows Vista to take up to three years, according to Dell. The firm, which has moved to offer services on top of its traditional hardware business, said that Vista can deliver savings for organisations, but they need to plan well in advance of deployment.

Vista has been available on new PCs for about six months, but is still largely selling to consumers while enterprises are holding back, according to Dell's client services business manager for EMEA, Niall O'Callaghan.

"Enterprises are not investing as much effort in moving as we'd like them to do," he said, but added that interest is growing in Microsoft's latest platform. Customers can see cost savings because Vista enables firms to operate fewer system image builds, for example, cutting down on maintenance costs.

O'Callaghan advised firms to plan well in advance for a Vista migration; to use new technologies such as assessment tools that can flag up potential problem areas; and to go for 'light touch' deployment options that will minimise the eventual cost of rolling out Vista by cutting the number of desk-side visits technicians will have to perform.

"A lot of customers don’t realise [migration] can take 12-18 months before you even get to deployment," he said. "There has to be a lot of preparation effort in application packaging and testing. About 20 percent of applications won't work with Vista at the moment and will need remediation."

Firms must also plan end-user training to use Vista, or they will face additional costs further down the line, he warned.

Customers Dell is working with are typically looking to start the process towards the end of this year, according to O'Callaghan. Most aim to put Vista onto new hardware to minimise any migration troubles, but this is being approached by putting Windows XP onto new Vista-ready boxes as current systems come to the end of their life, so that all desktops will be ready for a future switchover.

Some US customers will have early adopter users running Vista by the end of this year, according to O'Callaghan, and will proceed to a full roll-out according to how smoothly the process goes.

Dell said it is positioning itself to help firms migrate, as it can offer assessment and deployment services and supply new boxes with customer images pre-installed.

"We need to position ourselves as product leaders, someone enterprise customers can trust," O'Callaghan said.