Just also know on a Black Macbook, you either have a GMA950 or a X3100 - both intel integrated GPU's - there will be some functionality lost when using Final Cut...
Some FxPlug filters are not compatible with integrated Intel graphics processors.
That's for FCE, FCS2 I think had the same disclosure; FCS3 claims they are not supported at all.
Keep in mind you'll also really want to get an external firewire hard drive (in your case, I'm pretty sure a FW400 drive, I don't know of any Macbooks short the pro line to have FW800) to use for your scratch/media drive as you don't want to use your OS drive to edit with (there are many important reasons to this, including system stability, hard drive longevity, hard drive space requirements (video editing takes a lot of space), potential hiccups during periods of time where the OS tries to access the HD while the video editor is attempting to use the HD, etc.)
Yeah, Final Cut does take a lot of space - this may also be the time for you to consider upgrading your hard drive.
I know FCE would have probably been an easier package for you, but you wouldn't have many options when it comes to DVD authoring as FCE doesn't come with any tools to handle that. You would need to use iDVD or find some other third party package, and there just aren't many out there (granted, this may not be important to you).
The reason I had actually asked if you used iMovie '06 or '08 or '09 was actually because iMovie '06 was the last iMovie (AFAIK) to have a timeline for editing - that feature was removed in '08 and '09 where (as Oneironaut noted) MovieMaker is now much more similar due to its' continued use of timeline based editing.
To answer your other question, no I'm not a pro video editor, (well, I guess technically one could say I am since I have and do get paid to do video editing, but I don't consider myself a pro compared to many other people out there; if I were to describe myself, I'd put me more in the "prosumer" area
) - professionally, I'm the IT/network administrator for a technical school; but I fill multiple roles there, including handling editing and DVD production for the graduation videos and whatever other videos they need edited/titled/dvd produced/video for web/etc. I had done other video work in the past for a small video company, but my bread and butter money comes from IT. I'd have more to learn and need much more advanced experience before I feel I could enter the video production world as my sole source of income - but that's ok - I like where I'm at and what I do - plus when it comes to here, I can help with the easier questions and leave the more complex / advanced questions for those that understand that level of the programs.