Last night, I did several tests.
First, I have Abit VP6 machine that runs gentoo-linux. I took one of small harddrive and installed Windows XP on it. After that, I installed RecordNow DX that came with LiteOn 411s. Confirmed UDMA-2 and able to burn DVD+RW with Pioneer DVR-106D.
I have also installed DVD burning s/w - K3B in gentoo installation and able to burn with RitekG04 in 15 minutes.
I then re-installed to Abit SR7-8X. I have changed DMA mode in BIOS. First, I changed it from 'Auto' mode to 'DVD-ROM'. I changed I/O mode to 0, 1, 2, and Auto.
I tried to burn with UDMA on on XP - but no success.
The only option I have is to install a fresh copy of Windows XP on SR7-8X to see if that helps. I will do that this weekend.