I have an ~4-year-old machine with a Triton II chipset set up ina lab
rack. I find I need to hang about 80 gigs of disk off it.  Can I
remove the CD and stick two ~40-gig (currently UDMA) drives on this
machine, one on each channel, or with the UDMA drives not work on this
old chipset? Does it matter that the high-density drives are rated for
UDMA / 66, or (like scsi) will newer drives work with older
controllers?  Or will I run into stupid c/h/s limits?

Sorry to ask such a dumb question, but till now I've used SCSI
precisely to avoid this stuff. But the price difference is big.

(yes, I should get a new motherboard. But the case is AT, not ATX, and
I only have a couple of days to get this set up).

Here's the dmesg output, verbatim, if it helps:

pci0 at mainbus0 bus 0: configuration mode 1
pci0: i/o enabled, memory enabled
pchb0 at pci0 dev 0 function 0
pchb0: Intel 82437FX System Controller (TSC) (rev. 0x01)
pcib0 at pci0 dev 7 function 0
pcib0: Intel 82371FB PCI-to-ISA Bridge (PIIX) (rev. 0x02)
pciide0 at pci0 dev 7 function 1: Intel 82371FB IDE controller (PIIX)
pciide0: bus-master DMA support present
pciide0: primary channel wired to compatibility mode
atapibus0 at pciide0 channel 0
cd0 at atapibus0 drive 0: <CD-ROM CDU76E, , 1.0g> type 5 cdrom removable
cd0: 32-bits data port
wdc_atapi_get_params: drive 1 not present
pciide0: primary channel interrupting at irq 14
pciide0: secondary channel wired to compatibility mode
pciide0: disabling secondary channel (no drives)
cd0(pciide0:0:0): using PIO mode 3