A bare minimum system would comprise a pc that you can buy at any store for as cheap as possible, cheap-o monitor and printer as well and no tablet. Here in the states I could get that for about $500. The software is all freebie: Gimp for the art and image manipulation (similar to Photoshop); Blender, Bryce 5.5, or SketchUp for any 3d work; Inkscape for vector drawing; and Open Office because these people will be communicating with each other. To learn how to use this stuff there are books, online tutorials, and us here at The Guild.

Top of the line system would be a custom built rig by some company like Alienware (my dream system is about $15,000 with a big screen monitor and good printer) but newer rigs use multiple monitors. The Cintiq would be a must for this as well so that adds $5,000. A large format printer runs anywhere from $2,000 to $30,000. You should also get a large bed scanner, not one of those all in one printer/fax/copier/scanner things as those are crap (no idea on price). You might want high-speed internet access for some reason. You can get an Adobe bundle of programs for around $1,000 (Photoshop and Illustrator); other Adobe products (Dreamweaver) are good too for stuff like web and flash; and some professional GIS software (no idea on price); Maya is what they used to use before the Pixar computers were built so that adds another $2,000. You might want some CAD software for architectural work and Microsoft Office (wouldn't recommend that but it's pretty common). You will also need someone to teach people how to use all of this and these people will need months of practice.

That's a hefty price tag and the results aren't really that much better from the cheapo system...unless you want to make your own "Finding Nemo" movies. I use a "middle-of-the-line gaming system":
Gateway FX6800, Intel i7 quad core 920@2.67 gigs with 3 gig memory bought at Best Buy for $900
Soyo 24 inch lcd monitor for $250 from Office Max
Wacom Intuous 2 tablet for $500 (back in 2003)
Photoshop CS and Illustrator 10 bundle for $900 (back in 2003)
I have Dreamweaver ($700) but it was too complicated for me so I use it as a doorstop
Canon scanner for $300 from Best Buy
Canon printer for $250 from Best Buy
This comes to around $4,000 but there is also
HP DesignJet 430 24 inch black and white large format printer for $7,000 (back in 2001); and Dragonfly GlassEye 2000 ($600) This is mainly for my stained glass work but I use it for other stuff as well.

So for most applications any standard or middling setup is going to be good enough to do some really nice work. The cheapo way will get you some pretty decent results and with enough practice you can do some really nice work. The high end system is a waste of money unless you want to go into making videos for tv shows and movies. Heck, some of us here at The Guild could probably do up some good animated maps for a Travel Channel or History Channel show.