First, a quick clarification: There is no difference between DMA66 and UDMA66. It just depends on where you're reading it.
That said, I must also say this: I currently have a Fujitsu 10.8GB drive that I use for recording (I backup files to CD-R when I'm gettin short on space). It's set up for UDMA33, not even UDMA66. Using
the Cubase VST performance meter, the processor meter ALWAYS maxes before the drive meter does (not that my CPU maxes out very often). In fact, even in decent sized mixes (24 tracks), the drive meter RARELY reaches half.
The secret? This is where your choice of software comes into play. Cubase offers a great deal of adjustability as far as drive caching. The higher the cache setting, the less your drive needs to work to keep up. Everyone seems really gung-ho on 7200rpm drives. I'm not convinced that they offer that much more performance. 5400rpm has served me wonderfully.
Which brings us to the subject of RAM. For digital recording on a PC, you can't really have too much RAM. Very little affects your availbale number of tracks more than your availabe memory. Thankfully, RAM has become quite cheap of late (relatively, at least). Check this site:
www.buymemory.com
These guys constantly stay on top of the RAM market, and offer the lowest prices I've seen ANYWHERE (no rebate BS either). And no, it's not generic RAM. It's all good quality stuff.
One more thing that I must say: YES, Promise offers an excellent and fairly-priced UDMA66 controller. In fact, I own one. The benefit being that the controller takes a great deal of the load off of the processor for drive access. Using the onboard motherboard controller can often be pretty inefficient.
if this helps even one person, it was worth the post...