I've never used the portalign, but the $27 crafstman drill guide
(Sears item #00967173000
)they are selling isn't too bad. I have one and like it pretty well.
Here are my caveats:

1. Expect some profanity to eminate from your mouth while setting it
up
2. Don't trust the angle guide. Use layout tools to determine your
angles
3. You may want to replace the included depth stop with something a
bit sturdier (Although I use the stock one)
4. You can't use the springs and the depth stop together. This is
pretty annoying.
5. No keyless chuck

Other than that it works pretty well. Comes in handy over a drill
press when working with sheet goods. I'd also recommend dedicating a
drill to the guide rather than switching out.

Jay