If you started the new file with 600 PPI at the final dimensions it should print pretty well. My guess is that what you are seeing is aliasing and not pixilation. You can get rid of some of that in the text with “Smooth”, but you always get some aliasing with smooth curves using raster. If your friend can print the PSD you should try to avoid rasterizing the text.
You should use a vector program for a logo. Vector images don’t have aliasing. The best vector program is probably Illustrator. But there are some good free programs available.
http://www.freeserifsoftware.com/sof...us/default.asp