Ide caviar 16mb vs ide hitachi 8mb

hi Im stuck with two choices and Im leaning toward the hitachi but the wd has a 16mb cache, which is better:

Manufacturer : Western Digital
Model No: WD5000AAKB
Capacity: 500 GB
Edition: Caviar SE16
Form Factor: 3.5"
Rotation Speed: 7200 rpm
Cache: 16MB
Access Time: 8.9 ms
Interface: IDE (PATA)
Data Transfer Rate: 100 MBPs

Manufacturer : Hitachi
Model No: P7K500
Capacity: 500 GB
Edition: Deskstar
Form Factor: 3.5"
Rotation Speed: 7200 rpm
Cache: 8MB
Access Time: 8.5 ms
Interface: IDE (PATA)
Data Transfer Rate: 133 MBPs

I run a lot of videos mostly in 720p or >, so speed and reliability(product life) are my main concerns.

Also is it possible to run the primary drive (c from a pci sata interface card?? I think not but I could be wrong? My motherboard is ide, I was planning on running an ide primary and a sata secondary drive. The pci sata card has an internal port (I have 2 cards).

Thanks for any help

Yes you can run a primary drive from a PCI SATA card. I ran a RAID 0 primary with 2 SATA Seagate 160s from a PCI card with an old Gigabyte 865PE chipset. No onboard SATA it was a first gen LGA775 board. It did fine and I think I paid $15 for the card.
If you do that dont even bother with IDE drives.....SATA will be faster with the card.