For years I tried to create professional looking sheet music using Microsoft Word or by creating jpeg files, but the result was always less than satisfactory. The best solution by far is to create pdfs which are almost universally the accepted standard. You can pay $1000 for the Adobe software program that creates pdf files, or, if you're a musician on a tight budget but you don't want to compromise on quality, go for one of the following free options that will do the job just as well.
I recommend pdf955 as my first preference. (The results are clearer and there is no tag associated with your printed music, but pdf4free works well too if you don't mind the tag.)
Pdf995
Pdf995 makes it easy to create professional-quality documents in the popular PDF file format. Its easy-to-use interface helps you to create PDF files by simply selecting the "print" command from any application, creating documents which can be viewed on any computer with a PDF viewer. Pdf995 supports network file saving, fast user switching on XP, Citrix/Terminal Server, custom page sizes and large format printing. Pdf995 is a printer driver that works with any Postscript to PDF converter. The pdf995 printer driver and a free Converter are available for easy download. (Recommended)
PDF4Free - Freeware - Create PDF for free
PDF4Free creates PDF files from any Windows application running on Windows NT (SP3+), Windows 2000, Windows XP and Windows Server 2003. The software installs itself as a print driver, all you have to do is to click "Print" from your application to create PDF files. PDF4Free is complete freeware PDF creator. Users may create PDF files as many as they want. However, the features of the software are limited to PDF creation with font embedding, title, subject, author, keyword information embedding. The software is free only for personal and noncommercial use. Anyone who wishes to use the software for business and commerce should purchase PDF4U family products. All PDF documents created by PDF4Free will be tagged, i.e. "PDF Creator - PDF4Free v2.0" will be tagged onto all the created PDF documents. The sole purpose of the tag is to spread the free PDF creator software to more and more people.
Open Office
I have downloaded and tested this software ( a free alternative to the Microsoft Office suite! ) and it has the ability to create pdfs. I found the "Drawing" program the best.