Yeah, the Dual 1.25 processors do help it out, especially in Mac OS X (the extra processor is basically useless in OS 9, save for the very few applications that actually use it). My first one was also a Single 1.25 GHz machine, which I subsequently sold after I got my current Dual machine.
Mine has two 250 GB drives on the internal bus, and a 1 TB drive on a SATA card. It's no speed demon by modern standards, but it's no slouch, either. The SATA card, even though it's only 1.5 Gbps, is substantially faster than the internal ATA buses, so you might eventually consider getting one.
You could also overclock the CPUs a bit, if you have the skill to do it. I think you can get them up to 1.5 GHz (or maybe 1.4x), which would be a nice boost. I would do this, but I don't have the nerve.
c
Mine has two 250 GB drives on the internal bus, and a 1 TB drive on a SATA card. It's no speed demon by modern standards, but it's no slouch, either. The SATA card, even though it's only 1.5 Gbps, is substantially faster than the internal ATA buses, so you might eventually consider getting one.
You could also overclock the CPUs a bit, if you have the skill to do it. I think you can get them up to 1.5 GHz (or maybe 1.4x), which would be a nice boost. I would do this, but I don't have the nerve.
c