DMA transfer mode can increase the transfer rate of your DVD-ROM drive to one that is suitable for DVD playback. If you can playback DVDs without a problem, with DMA not enabled, then this step is purely optional. Also note that newer versions of the Intel drivers have DMA enabled by default, and you can no longer use the method below to enable it.
To set the DMA mode, or to check whether it is set or not
go to Control Panel under Windows 9x => System => Device Manager tab => expand CDROM tree (for Windows Me/2000, check under Hard Disk Controller tree) => right click on the listing of your DVD-ROM drive and select properties (for Windows Me/2000, right click on the listing of the main Storage Controller and select properties) => Select the Settings tab. (see below)
Here, you can also check your firmware version and also whether your DVD-ROM drive has the correct drivers. If the drivers are incorrect, then you will not see the full brand/model number under the CDROM tree.
If you have a non Intel based motherboard (eg. VIA), the bus-mastering drivers for your motherboard (eg. VIA's 4-in-1 Drivers) may include an utility to enable DMA mode - you should use this utility, instead of the method above (as it won't work).
Checking your DVD-ROM's region settings
Not all DVD-ROM drives are created equal. Some DVDs are region free, and some are not. To check if your is free or not by default, click here. You can also use an excellent program made by the guys at Visual Domain called Drive Info (download by following the link).