Best MAC to use with PCI 324 DP4.5 - well 3 questions really

[MR Booth]

I've had trouble running DP 4.5 with my early model G4 (one of the first models - 366mhz or something; 9 Gig hard drive 526mb ram). If I recordselect an audio track it takes about 10 seconds to start running. It made a small difference when I deselected multirecord or multitrack record or some such. Any ideas here for a solution. Is it just ram?
I went back to my G3 to do some recording recently! I haven't even bothered loading 4.6 as I think it needs a newer version system software.

While I'm waiting to see how the intel G5's stack up I am considering buying a faster temporary computer. I had a G5 2.0 dual lined up (Q77) and then I realised I probably can't run the PCI 324 card in it. Can I?

What's a good machine to buy that doesn't require me to also update the PCI card (who knows what the intels will require and maybe I'll just go to a traveller or something). I'm currently using OSX10.3 but anticipate updating that to 10.3.5 or newer or is that also an issue?

It would be great if someone can give their expertise on this!

Thanks, Mike