Experience shows that eyeballing a few characters works most of the time, but it's a terrible habit IMHO. Not only is it much more fool-proof to have the md5sum
do the checking for you, it's also simpler (since you only have to look for an "OK"). Hence, I second rayfordj
's suggestion that you use a checksum file.
EDIT: Heh, just noticed rayfordj had already posted an example of the -c option.
md5sum example.txt > example.txt.md5
md5sum -c example.txt.md5