Ooooh, there are more than one thing I would start simultaneously.
1) The Ultimate Dungeon Master Computer Aid. Includes all major published material for d20. Add-ons for other systems available. Among the variety of features, it would include the Ultimate NPC Generator, which is a program which you can control via command-line with an SQL-style syntax (or with a front-end). Think entering something like "GENERATE 5 NPCS WHERE race='ogre' AND 0<=level<=3 AND (class='barbarian' OR class='fighter')" and *poof* you get 5 full statted ogres, some with class levels, preselected feats and skills which you can still modify with a few mouse clicks, pregenerated inventory, description, and all you have to do is place them on the electronic battle map. Yay! If you aren't as geeky as me, you can use a handy dialog box.
Hey, you said unlimited resources? Invent something that generates a 3D picture of the battle scene, and something else that generates randomized backgrounds for NPCs.
Can you tell I'm lazy?
The program should be designed by the world's leading experts in software engineering and usability so that it automatizes everything that can conceivably be automatized and can be learnt in a few hours.
2) Dominia d20. Calling it Magic d20 makes people feel ill, but I still would love it.
3) THE D&D massive multiplayer game, applying all 3e rules as they are (there's some overlapping with project #1, which will be used to shorten development times). And since we've got unlimited funds, hire all the world's greatest experts on language processing, neural networking, artificial intelligence, and produce something that detects and eliminates PKs and idiots in general. For example, saying "l33t" should result in your head mysteriously exploding, and going around killing random people should result in a computer-controlled good-aligned adventuring party of twice your level coming after you within half an hour.
4) The Ultimate Dungeon Master Aid Hardware, running #1. Giant hi-res screen, 5.1 sound, smaller displays for each player, all controlled by the master's terminal. Broadband internet connection to other such hardware to play with friends in teleconferencing mode, and to download fan-made addons. The master's terminal has a 25'' flat touchscreen. Enough processing power and RAM to run everything smooth. Everything is connected on wireless. Runs linux.