So, after a month of contemplating and sourcing the right parts ... I broke down and bought a Gateway laptop, model MT3421
Thanks to everyone for their interests, remarks and help with my computer build.
Overall, I determined that mobility was/is a little more important to me than a powerful desktop. Now I just need to buy me a new copy of XP Pro, since Vista is such a horror to deal with on a daily basis. But that's for another thread, another time.