If you find most scanner software faffy and just need something that will let you scan a document and create a PDF file from those scans, then you might like Scan to PDF, for Softi Software:
http://www.softi.co.uk/Scan to PDF can interface with most standard Twain desktop scanners and can scan to multi page PDF documents even if your scanner does not have an automatic document feeder.
The interface is uncluttered and simple to use, and this is the only scan to PDF software I've found that will let me scan landscape printed A4 and produce a landscape A4 PDF. All the others created the page as portrait, meaning it had to be rotated in the Reader view settings!
Price-wise, it's affordable at under $25 too.
Softi also have ScanWiz, a PDF scanning program, also very simple to use and supports scan to pdf & opening multi page tiff's & fax documents. It can save documents as compressed TIFF or PDF as well as many other popular image files. ScanWiz currently costs just under $50 for a single user licence.
Softi have a feature comparison matrix here:
http://www.softi.co.uk/products.htm
