public/private key question with regard to ssh logins

I just happened to think today that I was using the same public/private key on all my shell logins and I genned a bunch of new ones for each shell. Which then made me notice that the default within putty application I was creating them with was 1024. I'm pretty sure account where I su up is at a higher length(2048), but that made me think.

What should I be using? Even on my b.s. accounts, is 1024 high enough? Major shell logins, should I doulbe the 2048? Can I?

I am a firm beleiver in public/private key logins... But, I just realized that I am unsure what is the best way to do it... Other then adding a pass phrase to use it.

Dan