I think you will have trouble finding a SATA2 PCI card that is not linux compatible. I have this one
http://www.newegg.com/Product/Product.aspx?Item=N82E16815280005
2 SATA + 1 eSATA.
for esata, I dont like anything out there for pre-built esata drives of good quality. I suggest the following combo
http://www.newegg.com/Product/Product.aspx?Item=N82E16817173042
and this drive:
RAID Edition 1TB
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136313
or this drive
Black Edition 1TB
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136284
You can ebay a SATA to eSATA adapter or get one off meritline for like $5-$8 and that would give you 3 eSata ports.
The raid edition drive is certified for non-stop use. both have a 5
year warranty. People have reported some modern drives to fall out of
raid arrays and require re-syncs often. Western digital will replace a
raid edition if this is an issue but not anything else. These are
about the fastest drives you can get which is ideal for backuppc. The
Samsung F1 drives are also very fast (maybe faster) but have a shorter
warranty of 3 years.
I run the raid edition WD in a server and have the black edition WD in my home workstation and am satisfied with both.
I can tell you that you will have a bandwidth issue and here is the math.
PCI = 32bitx33mhz = 132MByte/s maximum thoroughput. Because backuppc
will be handling the data, you will use the bus twice during backups
(PCI>CPU>PCI) but PCI is duplex so thats 132MB in and 132MB out.
That must be shared amount all devices so anything that is recieving
data like the hard disks will share that 132MB and so on.. Basically
SATA 300 wont be of any use to you because you dont have the
bandwidth. That should be ok but you wont get the full burst speed of
the drive from cache.
I am assuming that you are limited to PCI because of the P4 and you
typically didnt find anything but a PEG slot which cant be used for
anything except graphics card unless this is a very recent P4 system.
I also recommend newegg.
