Contact form - plug in or made?

hello all.
using this blog post to insert a contact form in a wp site i am helping build.
& of course tweaking and changing some settings as I go along.

what i wonder is:

  1. any quick way to test for mysqul injections issues?
  2. if i wanted to use a plugin instead, can you guys recommend a good, safe easy one?
    thx
    D

I use contact form 7
So far I haven’t had any problems with it.