1) Apollo Pro 133A DOES support 512MB DIMMs, is "supposed" to support at least 1.5GB.
EDIT: 1.5GB due to it having 3 slots, but the chipset can support 2GB. More Apollo Pro 133A spec available
from the source.. However the source claims some lesser features from an older southbridge than this has, like ATA66 instead of the ATA100 it offers.
2) It is "most likely" that you do not need an expensive Upgradeware adapter for a Tualatin, but could instead use one of
these adapters.
3) Apollo Pro133A is a much better choice than a BX board -
- BX has only AGP 1 (1X/2X 3.3V)
- Typical BX board would struggle to provide enough amps for a Tualatin
- BX uses ONLY low-density (more expensive) memory, max 256MB per slot
- BX has only ATA33, while this Pro133A (w/686b SB) has ATA100
- BX only provides 2 USB ports vs Pro133A's 4 ports.
- Pro133A with a modern BIOS and Via 4in1 drivers, outperforms BX.
As for the PCChips board, it's junk. Newer PCChips/ECS are better than the old stuff.