Changing individual pieces of text in WordPress admin

I am trying to change the individual pieces of text in the WordPress admin, e.g. “Need help? Use the Help tab in the upper right of your screen.” (in WordPress 3)

This is because I aim to move the Help location! Other pieces of text I need to change simply because I feel it is not professional enough, and I am using this as a CMS for a big company.

Is there any way to quickly edit these pieces of text, using the translation, without a) installing a big plugin and b) having the translate everything?

Preferably I would be able to drop some code into my ‘rebranding’ plugin that I am making

Thanks.