20mm hubs are 110mm wide
QR hubs are 100mm wide
There lies your biggest problem.
You can get a 20mm rigid fork, I can't remember who makes them, but talk about overkill.
You can get a new hub and have it laced to your wheel... but your best bet would be to buy a new QR front wheel. Depending on your riding, you could get away with a lightish rim (if you kill front rims, there's problems), and you could probably get a half decent cheap wheel for the same price it'd cost to buy a new hub and have it laced.