How to sort numeric and literal columns in Vim
Solution 1:
If you have decent shell available, select your numbers and run the command
:'<,'>!sort -n -k 2
If you gonna type this in visual mode, after typing the colon, markers '<,'> will appead automatically, and you'll only have to type the rest of it.
This type of commands (:[motion]!) is called filtering. You can learn more by consulting vim's help:
:h filter
Solution 2:
Sort all lines on second column N by using Vim sort
command, e.g.
:sort /.*\%2v/
Reference: vimtips.txt
Solution 3:
For vim7 I would go for:
:sort n /.*\s/
This will sort numbers ignoring text matched by given regexp. In your case it is second column.