Lightroom & RAW+Jpg
I have a Vista x64 machine with 8 GB RAM and overclocked 3.2GHz quad core, over 4 years old now, and LR 4.1 runs fine. I don't import huge numbers of RAW files at once though, only have 155 total as I just started shooting RAW last month.
I do shoot RAW + JPEG and initially dump all to a temp file on desktop. I use the JPEGs to quickly review in MS Office Picture Manager and delete the rejects. Then sort by file name and delete RAW files that don't have an associated JPEG. Then move JPEGs to storage drive where they're shared over network and backed up each night. These are just for having the pictures available in the meantime while I do the RAW processing. (With a baby nearing 1-year-old, I don't get to spend much time on it.) Then move RAWs to storage drive where they're permanently stored, then import to LR. After editing I export JPEGs and compare to OOC to make sure I'm actually doing a better job of it since I'm new at it. Ultimately the original OOC JPEGs get replaced with LR exported JPEGs once I'm happy with the edits.