Office network 4 Macs still running 10.4 Tiger. Shock horror, call me crazy if you wish.

Why? Because it works! There must be thousands (tens of thousands?) of other Tiger-users still out there, just like us.

Last time I bought replacement Macs, I installed Tiger onto them. Now I'm considering replacing the replacements, because one of them has a small screen and the other is so noisy (it's a "windtunnel" tower). But they both work fine, as do the other two flat-screen iMacs.

The main reason for never upgrading OS from Tiger is that all our applications work, and I'm the scaredy type who will never forget the horrific nightmare of getting off OS9 and onto OSX a couple of years ago. This is an office, not leisure use.

Applications in daily use: AppleWorks believe it or not, in daily use. Pages and Numbers. DeltaGraph. FileMaker Pro. Some MS like Excel and Word but only when in extremis because people have sent us things in those applications and require translation back to them, in reply. All the others are regulars like Firefox, Mail, iPhoto. I use IE occasionally for one website which does not work on Firefox.

So here's the crazy question: when* I source two more Macs as replacements, they'll come with Leopard or higher.

Go through another potential nightmare of upgrading entire office to higher than 10.4, or just go ahead and instal 10.4 on them when I get around to sourcing the replacement Macs? I'm looking at Amazon for good deals - not brand new ones.

*there's no rush but we have the cash atm, and the (1) small screen and (2) noise from the windtunnel are beginning to bug me.

Hope you can make sense of all that. Thanks.