f*ck that. i'm going to tell you what i've had and what i have now.
I had a 1.2ghz AMD CPU running 512mb RAM and dual HDs that were 10000RPM one for applications and one for audio files. I had a Frontier Design wavecenter PCI card connected to a Tango24 D/A/D with a Mackie 1604 as the pre-amp until i got an FMR Audio RNP.
Rarely had a problem with it running Sonar2 with Waves, Autotune and occassionally Sonitus fx. I would occassionally record up to 8-in at a time, but most of the time i'm just recording 1 or 2 stereo tracks (keyboard and drum machine in stereo at the same time).
Now I have a 3.0ghz Intel P4 laptop with 512mb RAM, 1 7200RPM HD, 4 USBs and 1 Firewire. Its connected to a Tascam FW-1884 (via firewire). the tascam has the keyboard and drum machine connected via MIDI and as audio inputs (stereo). the laptop also has an external mouse/keyboard [usb], IOMega Zip drive (also connected to the drum machine/sampler) [usb], dual monitor, and Hauppage winTV [usb].
I can watch TV on one monitor while i'm recording midi via Sonar (on the other monitor), but watching tv and recording audio at the same time is something i haven't ventured to try.
I also have an Edirol FA-101 that i use to record my band during practice and to record vocalist at their home.
both the tascam and the edirol work great with Sonar on the dell inspiron 9100.