Photoshop >to> a photo company. What to save it as?

I have a picture that I edited in Photoshop (from its original so its 300res) but I want to know the best way to save it for a photo business. Most tell me that JPG is fine. Will saving to jpg on the highest quality lose any of the quality? Is there a better way to save it in preperation of going to a photo place?

TIFF is the usual format for commercial printing, so I'd stick with that.

If the file is to be sent to a printers (as in Offset printing) better ask the printer for which file format and which colour profile he wants embedded, if any. Like Alexis says, it's usually .tif.

If it's to print as a photo at a photo finishing place, .jpg is what they want. I had saved my photos in CMYK and .tif and they never could do anything with them: so I had to take them home again and resave them in .jpg. I can't recall if they accepted Adobe RGB (1998) or sRGB for a colour profile though. You might be better asking them too.

TIFF is a pretty standard file. You will lose some quality with a JPEG even at the highest setting.
It would be smartest to ask what file they are looking for. Asking about color space and such will be helpful too so that they get exactly what you see on your monitor.

In the "save as..." window what does the check-box line "embed color profile" mean?

It's to make sure that the colour profile you assigned to your image while you were working on it will follow the file.

But like I said earlier, make sure what colour profile the printers or the photo finishing place wants and ask for which file format they prefer.

If you embed the wrong colour profile for which their machine isn't calibrated for, the colours of your photo will look off from what you expect and what you see on your monitor.