ATA (IDE) Hard Drive Specs

With what appears to be a dwindling market supply of ATA drives here in NZ (and elsewhere?), and the unlikely event of my owning an updated Mac in the near future, I'm thinking I ought to make a purchase sooner rather than later. These are what I'm considering:
• Hitachi Deskstar P7K500 Hard Disk Drive, 250GB, 7200rpm, 8MB Cache, *ATA-7/133*
• Seagate Barracuda 7200.10 ST3250620A 16MB 250GB
• Seagate Barracuda 7200.10 ST3250820A 8MB 250GB.

Could someone please explain:
1. the *data* of the Hitachi - what does the 7/133 mean?
2. The potential advantage in the Seagate of a 16 Mb cache [there's very little price difference.]

ATA-7 would be the bus version, in this case denoting 133 MB/sec
ATA-6 is 100 MB/sec
And so on down the line

The advantage of the higher cache is in read ahead and write times.
With all of the past reviews and comparisons I've looked at, the difference is extremely negligible within a specific manufacturers line and likely as not, you would see no noticeable improvement with the higher cache in an internal drive. Might see it with an external.

You'll see much bigger differences between manufacturers than you will between cache sizes within a manufacturers line.

Having said that, I always purchase the largest cache size of the drive I've decided to get for myself. But, I have no qualms in recommending the smaller cache drives to friends that need to save the few dollars. Nor am I worried that they're missing out on some extra speed it may or may not have provided.

Thank you bobtomay, and in reference to a post in Apple Desktops about installing a second drive inside a G4 MDD - do ATA-SATA adaptors work with Mac machines? Not that I could use one inside my eMac, but others may be interested.

I've not really read much about those converters. As with everything else, I was an early adopter of SATA and at that time, my computers rarely lasted me longer than about 12 months and I didn't keep backups so never had spare drives lying around.

I've never personally tested them out. From the little bit I have read, I would think if the converter will fit in the machine, it should work since it sits between the IDE PATA and SATA interfaces. OS, motherboard, etc, shouldn't come into play. They're only around $10-$15 over here, so you're not out a lot if it doesn't unless you're buying a drive at the same time hoping it will work.

The ones I have seen are all one way. You have to make sure you buy the proper one to go the direction you need, "IDE to SATA" or "SATA to IDE".

Have used an eSATA PCI card in a MDD G4 mate and not worth the effort and expense. Stick with the ATA drives and have always found Seagate good value. Hitachi took over manufacturing hard drives from IBM as they produced bombs known far and wide as DeathStars. Do a Google on DeathStar.

Whilst Hitachi seem to have a good name, however three dead DeathStars was more than enough for me and cannot work out why they did not re-name the line!