Presently, on a G4-400, just a bit more powerful than your celeron, 1G ram, and Tons of HD space (320G over 6 drives) I'm able to easily record 32 tracks at a time with DP3, 2408MKII and 24i. If you've only got one drive you're using, that may be your bottleneck. If you're financially able to, go out and pick up another ATA66 or ATA100 drive, plop it in and then record a project with your data spanned over the two drives. Don't know if Sonar will allow you to do this, but it's a cheaper remedy than the new CPU. In addition, I used to use 4 drives for recording, and topped out at about 12-18 tracks depending on the number of efx I was running. Was easily able to handle 32 with 6 drives.
No matter which way you go, if you're serious about what you're doing, when you make your next CPU purchase, be it a PC (AMD chipset) or Mac, invest in an ATA133 RAID card and 4 identical drives. You'll be much more pleased with the response.
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