Photographing artwork for reproduction. Will 2820dpi be enough input?

I'm shooting some artwork for a friend. This first job is a 4' x 8' panel that will be printed to about 50% of the size of the original. I'm not sure that my Dimage Elite (2820) is going to give me enough input to get the quality they need.

I'm really no expert on film scanners, I purchased the dimage (ICE2) last year so that I could convert my film to digital format, and have never used it for this purpose before. Also, if you have any experience shooting artwork, please feel free to share any tips. :-)

I'm confident I can handle the job, but I'm sure there are somethings I will do inefficiently the first time around. Is there a film you like best for this type of job? (I'll be shooting outside in indirect light against a black back drop. I will shoot this with an Elan. I am planning to rent a better light meter, a 50mm L series macro lense, and will purchase the Kodak color patches. Should I add anything else to the list? My tripod is pretty sturdy. It should be it was built during the civil war and weighs about 800 pounds.

Finally, for my own purposes, I've used the bundled dimage software for twaining. Is it worth it to go ahead and purchase Vuescan? People seem to have good things to say about it.

Thanks so much,
Kristin