Monitor or keyboard upgrade

Hello all! im new at tom's so forgive me if i didnt post this the correct place.
I recently purchased a new gaming pc with good high end components like MSI GTX 670 2GB and i5 3570k.

I have my old screen a Samsung Syncmaster 226BW 22" (2ms response time) that i bought around 5 years ago, and have been extremely happy with, and still am. The screen stills works perfect, but the problem is that its native resolution is only 1680x1050p. Im wondering if it would be stupid to not have atleast full HD screen when im using a powerful pc.
Is the difference between 1680x1050 and 1920x1080 really big, or noticeable at least? The main reason i would switch screen would be because of the resolution, but also to get a bigger screen (maybe going 22" to 24").

The other option i have is buying one of the more expensive mechanical keyboards. Currently im using my old G11 membran one. It still works fine, but some of the buttons have started to become a bit annoying to press. I heard alot of good things about the mechanicals ones, and become quite interested in trying them.

So basically, what do you guys think would be the best option for me? Upgrade my screen to get a few more inches, and a HD resolution, or buy a good high end mechanical keyboard (like the Qpad MK-85 for example)? I only have the money to choose one of them.

I use my computer mainly for gaming.