I know there is a sticky about external hard drives, and I have already ordered a couple of Mini Stack V3 enclosures from OWC, BUT, I need a bit of advice of the type of HDD's to use.
My budget will allow me to get a couple of 500GB units (these will be used by Super Duper for alternating off-site data backup storage). I definitely do not want to go smaller than 500GB, hence my query re Seagate of W.D.
MSY have the Seagate SATA 500GB at $155 per & the W.D. 500GB at $124 per. I believe the Seagate has a 32MB cache whereas the W.D. has a 16MB cache. As I will only be using the HDD's for data backup storage and not everyday use, do you think I need the extra 16MB in caching that the Seagate offers? Also, I know some ppl have a preference for a certain manufacturer, myself I don't even though I have used and will be re-using 3 extra 320GB Seagate SATA's in my Mac Pro (one will be used for Time Machine). So, long story short, what do you recommend, is one quieter than the other?
Thanks.

I will say Seagate for the bigger cache and better warranty.

Others will say WD. Go for the one which you're happy to pay for. Myself, I will get Seagate drives.

Didn't think of the warranty period - what is the difference between them?

My Freeagent drive from Seagate has a 5 year warranty. I have 2, and no problems yet. I understand WD can be either 1 or 2 year warranty. HTH

im on the seagate free agent and it works decent.

I like the orange light thus I got the free agent!

ahhh, ok, so then all Seagates have a 5 year warranty?
Don't need the Free Agent as I already have the Mini Stack V3 enclosures - the Free Agent cases do look pretty cool though...

5 years on the Seagate.
3 years (I believe) on the Western Digital.

It could be less for WD but I'm sure Seagate is 5 years, since I have purchased a couple of drives off them (notebook 2.5" SATA) as well as a FreeAgent Go (love it)

A friend of mine's WD external drive just borked itself if that's any help?

Yep, got the idea - thanks everyone
Just had a quick sale over at OverClockers - sold an EIDE 200GB, 300GB and 2 x 500GB (all W.D.'s).
Got enough to pay for a Seagate 500GB SATA - could have got more, but I'm very happy. Should have seen it, it was a feeding frenzy....

I have 2 x 500GB WD SATA drives and they seem very noisy and vibrate heavily, which I don't like. However, I have had multiple Seagate drives fail on me in the past, at the worst possible times.

Having said that, you are relying on anecdotal evidence here. Don't. Do some research if you think it's worth it.

Thanks for the input Edge.

I actually don't have an opinion either way to be honest. I just sold 4 EIDE W.D. hard drives which have given me no problems whatsoever. Alternatively I am currently running 6 x 320GB SATA Seagate's in my water cooled pc, once again they have been extremely reliable. In fact three of those Seagate's are going straight back into my Mac Pro when it arrives this week.

I was really fishing for peoples experiences and opinions, however I was not going to make an ultimate decision based on that alone.

The deciding factors are:
PRO's
Seagate's have a longer warranty period.
The Seagate's have a larger cache.

CON's
Seagate's cost more.

2 to 1 wins - (the cost isn't really a factor as I sold off my old EIDE HDD's).

Get the Seagate then.

At least if it dies on you, you'll be covered by warranty and they'll send out a replacement (this has happened to me once in the past and they were quick to send out a replacement, once they received my dead drive - probably 3-4 day turnaround from Asia to here). This was a notebook drive (2.5" SATA) that I thrashed daily though.

The iMac that I am on (24" C2D Aluminium) came with a 500GB WD and it is fine, not to say that Seagate are duds either.