I need to perform certain sensitive operations on my computer (access important bank account, sensitive passwords, etc).
I currently have 1 mac, and my approach is to not install any closed source software.This approach is very limiting though, as there are many closed-source software that would greatly improve my productivity, and some are straight necessary for some of my business activities.So I am currently considering purchasing another mac and performing only sensitive operations on one (with only open source or highly trusted programs), and other tasks on the other (with a lower level of trust in installed programs).However the downside is that managing two computers probably adds a significant complexity. 
Is there a better way to achieve this? Thanks!