I'm in the exact same boat. I have a mATX Gateway K6-2 rig that the Mobo failed, so I'm in market for one. Truthfully, I decided because according to MOBOT, there's only a dozen of mATX K6-2 mobo's that were ever created, So likely I'll just get a new Case, and a P5A. For that list go to
Motherboard.org's MOBOT, set the interface to Socket 7 and the form factor to micro ATX. There's only 24 mobo's listed. And half of them are using SiS 530 which i have heard in my researching,
very bad things about so that leaves Aladdin V and MVP3/4. P5A-VM is very good in all likely hood considering how great P5A is, but finding any of these boards is the issue. There's only one mATX board I've seen for sale or on Auction's, and that was a PC Chips SiS 530 board that somebody used and said it was a terribly unstable board, so it should be avoided too. I'd just get a new ATX case and a P5A, or similar board. But, if you find a reseller selling a solid board, let me know, because I wouldn't mind using my current mATX case, but if I need 2 I will get a P5A/Case ok. Good luck, thanks.