In the early days of digital video editing, an export render could take hours! Not many applications are as hard on system resources as video editing, and rendering the final edit is probably the most system intense action of all.
Head on over to the Premiere Pro Hardware forum to see what sort of computer hardware the pros use for NLE (non linear editing), or to the PPBM5 site for a better look.
Also check out the specs on the Video Guys website