ok... well, as for system spec, we're using a p4 2.4, asus motherboard, 512 ram, a mout 2408, through the dm24, sata hard-drives and can run 24 tracks of nuendo with about 2-3 effects on each channel without much trouble. it tracks 24 sumultaneously too (16 tdif, 8 analogue IO on the motu) note, we haven't upgraded to nuendo 2 yet, but there's an upcoming point release for it that looks just about irresitable (the hold off has been the generic remote support in 2, and it looks like they've taken care of it)
In hindsight, I probably wouldn't recommend the audio end of this setup, but we do a lot of location work, so it travels really easily, and with all the io on the dm-24 makes remote tracking a breeze.
Anyhow, I've been using nuendo for a long time, if you decide to buy it, give me a holler with any troubles.
As for the cubase v. nuendo... they are now the same exact vst engine, the differences are the increased robustness of nuendo for film post work, and additional surround formats (as near as I can estimate, cubase only does 5.1?)
Wavlab is an entirely different beast, and depending on your method of working is a somewhat decent wav editor, but steiny is making it look more and more like their other programs... (check out the upcoming wavlab 5)
Anyhow, I hope some of this helps.
Regards,
Rich