Yes...I do fear a better soundcard may be in order. What is yours? For vocal recording I'd strongly suggest an USB or Firewire external box, something like Presonus or M-Audio, they start from ~$150 usually.

With a decent card the latency should be less than or at least around 10ms, which you won't really notice in vocal stuff.

BUT if you want the best solution, separate monitoring (not via software at all) is always going to be by far the easiest and best solution. (I always get crazy annoyed just remembering to mouse that 'monitor' button on and off when doing recordings...if only for that reason, a monitor mixer is great.)

I strongly dislike most Behringer gear for any serious audio work, but in the listening side of things they work just fine. I have for instance this:

http://www.behringer.com/EN/Products/MON800.aspx

And it's been super handy, allows for mixing in effects and for using two separate monitor speaker systems plus headphones too, all with their own volumes; very handy a device. Paid $20 for mine used.