The initial hurdle is that you must split the partition in two as each version of Windows must be installed on its own partition. You can go into Disk Management (an Administrative Tool through the Control Panel) and "Shrink" the current partition, then Create a new partition from the newly unallocated space. The other alternative is to use a third-party program such as Partition Magic. Neither method is foolproof, though, so there is a slight risk of data loss.
After that's done you can install Windows 98 on the newly created partition. However, the complication is that when you do Vista will likely be unbootable. You would then have to boot to the Vista DVD and choose the Repair option, performing a Startup Repair to current the problem. It's entirely doable, but it can get a little testy. Personally, before doing that I'd copy-and-paste any important files onto a flash drive or external hard drive, just in case. If you decide to press ahead and have any questions feel free to ask.
John
I have a new sony vaio with vista installed... I wanted it for all my photoshop and video editing work... I now cant even open one video in media player etc of adobe elements... all I can do is use quicktime.I can't even rip a cd!!!
very fed up I want to install windows 98 as well so I have the choice on startup...
can anyone help me do this... I'm a bit scared about losing access to vista and losing my work, as the backup facility isn't working on my version of vista!!!
thanks jonni

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