Can you trust your BIOS?

[Insomniac]

When your systm boots up, it tells you quite a bit of information. One of those things is the modes for your IDE devices (PIO X, UDMA X). Can you trust this information? I am hoping other people wonder this. I know most people will always know what there hard drive is capable of (ATA33/66/100, etc.), but what about CD-ROM drives? I have an HP9110i and Sony 32X Slot Load. I have tried looking everywhere for a definitive answer about whether my drives are UDMA capable or not. I want to know so that I can enable or disable 'DMA' in the Device Manager (I like Win2k because you can just select the option to run in DMA if possible). Anyways, my hard drives post as UDMA Mode 4 and my CD-ROMs post as UDMA Mode 2. Should I enable DMA?