should I get SATA drives for old PC?

[Steve Kleene <skdeb@syrano.acb.uc.edu>]

Before I build a Lenny system on my 5-year-old PC, I want to replace the two
internal hard drives.  I'm not too swift with hardware specs and want to make
sure I get the right drives.  I will probably get 500GB drives and do not
expect to set up RAID.

The drives now are Maxtor DiamondMax Plus 8 6K040L0 40GB 7200 RPM IDE Ultra
ATA133.  There isn't much of a selection anymore with the ATA100 or ATA133
interfaces; most new drives are SATA 3 GB/s.

The motherboard is an Asus P4P800 Deluxe.  It has two SATA connectors and
came with the cables.  The motherboard manual says, "The current Serial ATA
interface allows up to 150 MB/s data transfer rate" (i.e. >133).

So now to the questions:

1. What difficulties (if any) might I expect in setting up the SATA drives?
   A quick search found quite a few posts where people had to mess with the
   BIOS, add a SATA driver, etc. with this motherboard.

2. If I buy a SATA 3 GB/s drive, will this motherboard only give me 150 MB/s
   anyway?  In that case maybe I should just go with ATA100 or ATA133.  I
   assume either would work.

Thanks.