Single shots rarely take me more than a few minutes unless I've got dynamic hair, shadows, ray-tracing reflections, etc... all going at the same time. I've got about 1 GB RAM, a P4 processor (1.8 GHz) and lots of hard drive space (not that that makes any difference, but I just installed 2 new 120 GB hard drives and I'm pretty proud of the fact that I did it without wiping out all my wifes files. If that had happened, I wouldn't be writing this right now.)