I bought a western digital 160 GB Eide hard-drive, but is only working in PIO mode. Why don't work in DMA 5 or 6 mode? My motherboard is an Asus TUA266. I tried to update the driver but nothing, he's useing the driver from windows xp.

sounds like you need to hit the "delete" key as your computer is starting up and go to the FIRST PAGE in the BIOS (the blue screen that comes up) and set the drive to the setting you want (might "auto" it). If you are not familiar with how to do stuff in the BIOS just realize that it's pretty difficult to mess things up unless you have a really hot-rod motherboard with overclocking bios stuff. Don't dink around anywhere else, just in the hard drive section and you oughta be totally safe and fine. The main "movement" buttons in BIOS settings (there is no mouse) is the page up/down and arrow buttons on the keyboards. Once you have the Hard Drive set to "auto" or UDMA/UATA just hit escape to the main blue screen and hit the "f10" button to save and restart and you should be good- the BIOS will automatically detect the right settings for your hard drive. Should that fail, go download the Western Digital driver diagnostics and testing tools (two different apps) for your operating system from their website. Each app will easily fit on it's own floppy disk. Restart with the floppy in so that your computer looks at the floppy before any other drives (a standard default bios setting usually) and it will load direct into the Western Digital application. That oughtta fix just about everything or give you direction on what to do next. A few possibilities if you run into problems... 1. Your Mobo bios has the drive SET at that or can not recognize that kind of drive. You'll need to find the setting and change it in the BIOS- more bios stuff like the first thing... 2. Your mobo BIOS can not recognize the size of the hard drive (it's "too big"). Western Digital tools has a app in there (in the tools app) that will allow you to "change" the declared size and settings for your bios- a sort of "trick" to get past older bios issues with Mobos. One thing to note.... Unless you have a blank drive DO NOT alter the partition information in ANY way (the Western Digital tools will ask you for confirmation if you accidentally stumble that way) or your data on that disk will be VERY hard to recover, if at all possible, ever. If you have a new hard drive and want to set up come custom partitions the WD tools has a GREAT app for doing this! good luck

one other posibliity is you are useing an old 40 wire IDE cable , while you need the newer 80 wire 40 pin IDE cable.