I'll sell you an Abit BH6 for $35 plus shipping. It supports my Celeron 1.1GHz at 1466MHz, it should have no problem supporting the PIII 1.4. It also supports 512k Cache, as that's what most PII's came with. You'll need a Slot 1 to Tualatin converter for it, available for $20 from the american distributor for Upgradeware.
Oh, back to the question: I'd recommend a BX chipset board, maybe even a nicer one than mine. You could get a BE6-II v2.0 or BX133-RAID, for example. They support 256MB/slot, can't remember weather that board was 3 or 4 slots though.
Of course you could use that Tualatin adapter on an i840 slot1 board, with RDRAM.
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