Canon liDE 35 vs liDE 50

I'm new to scanners and am now buying one to scan in some photos for
my family that they want printed out on plain paper to enclose in xmas
cards. Then I plan to (slowly) go through our photo history (black &
white and colour prints) to put them online to share. I also need to
scan documents and books (very light work load) to include text and
images in research work.
The Cannon liDE series suits my spec (I'll be mainly using XP, but may
also use it on Windows 2000 Pro), and am now deciding between the new
35 model (which I understand is the "new" 50, but strangely
renumbered), and the 50. There are minor spec differences which don't
bother me, now I'm down to two areas.

1) Both have a 16-bit grayscale depth, but the 35 only has an 8-bit
external grayscale depth (50 is 16-bit). Can anyone explain what
difference this makes, or point me to an online explanation of
grayscale depth differences?

2) The 50 comes with more softwa Adobe Photoshop Elements 2.0
CD-ROM; CanoScan Setup CD-ROM, including: ScanGear CS (Windows/Mac),
CanoScan Toolbox (Windows/Mac), Arcsoft PhotoStudio (Windows/Mac),
ArcSoft PhotoBase (Windows/Mac), ScanSoft OmniPage SE OCR
(Windows/Mac), NewSoft Presto! PageManager (Windows) and NewSoft
Presto! BizCard (30-day trial version, Windows only).
The 35 comes with Drivers & Utilities, CanoScan Toolbox, ArcSoft
PhotoStudio, ScanSoft OmniPage SE.

I'm tempted to go for the older 50 (marginally cheaper)due to these
differences, but due to my lack of knowledge in this area am wondering
if I'm making too much of them.

Any thoughts on the above would be welcome.