5 - 10 years? I honestly can't see any pc being able to do that anymore. I am impressed your pII 450 made it this far
But with all the stuff going digital now, 5 years useful life is a dream I think.
I purchase web servers mostly now, so I may not be right on the ball with hardware for a personal machine but in your situation I'd personally go with something like:
p4p800 motherboard
p4 3.0ghz cpu
512mb ddr400 stick of ram (I dont think you'll need 1gb, unless you plan to play a lot of games, etc).
I like the maxtor diamond max 10 sata drives personally. I'd shoot for at least 200gb now, simply because the price is so cheap.
dvd burners are very, very cheap and a great way to store digital photos. I have a great burner, made by Benq.
As for video cards, I am not really up to snuff on the latest and greatest. I'd shoot for something with atl least 256m on board memory... other then that I am unsure (I run a radeon x800 XT in my machine, but I dont think you want a $700 video card
Finally, case and power supply are very important IMO. Stable power gives your hardware a longer life. My personal fave case atm is the antec sonata. Its been out for a while so the price is dropping, it is absolutely silent, great psu, and good airflow. Great value.
HTH