Oh, I almost forgot... Karen, Photoshop Elements 4 is four to five years old! They are now up to Photoshop Elements 8 (and if past behavior is any indication, Adobe will probably announce version 9 in September.) Personally, I would at least get Photoshop Elements 7 which you can still find on Amazon and probably other online stores as well - and it's cheaper because it's not the latest version.
OK, I just realized that everything I just said is really only true for PC's. Photoshop Elements on a Mac has historically had fewer versions. For example, there is a Mac version of Photoshop Elements 8, but the previous Mac version was Photoshop Elements 6 (i.e., there was no version 7 for a Mac). Unfortunately, I have no idea if Adobe will make version 9 for the Mac or not.
Hope this helps.