I bought a new mouse about a year ago... nothing speacial - Corsair Katar. I use a 24" HD monitor.
It's got adjustable DPI, up to 8000. The pre-loaded DPIs are 400,800,2000,4000 and 6000 with 800 being the default.
800 works well for the only game I play (World of Tanks) but is a tad sluggish...