Round-up and the like biodegrade on soil contact and when metabolized by plants (usually only one application) degrades into inert compounds. No residual chemical problem so relax and garden with confidence of a health environment.

You have touched on a very sensitive topic - Roundup - and you will get just as many "never touch the stuff" answers as you will "sure it is safe" answers. If you want to read some of the many previous discussions on it, just search 'Roundup' here. You'll find more than 2000 previous discussions on its pros and cons. So, the bottom line is, it is your choice.

Yes, removing the sod is somewhat labor intensive but then so is much of gardening, depending on the size bed you are building and it is good exercise. Invite a few friends over with their shovels and you can have it all done in a couple of hours and 2 Tylenol each. ;)

There are also many alternative ways to build a garden bed including raised beds, lasagna beds, Square Foot gardening, cardboard mulch, etc. that you can read about. They all have their advantages and disadvantages but are a bit less labor intensive. You'll find many discussions on these approaches over on their respective forums and on the Soil & Compost forum.

Good luck and enjoy your garden!

Dave