The problem is with the graphics on the macbook. It does not meet the recomended specs for FCP. That being said, your Mac came with I-movie HD which is one of the best consumer level editing packages available. You might find that it will meet what you need for a while. Additionally you can buy plug-ins that increase the functionality of I-movie and make it a much more powerful editing program(I actually discovered you have to download I-movie '06 for this, check out the article on the CF/X site.). (Keep in mind 90% of your edits should be cuts and dissolves anyway. Other effects are like spices, use them sparingly to enhance a production.)
I am not sure what the requirements are for final cut express are. It is essentially the same as final cut with a few proffessional features turned off. That might be a nice option for you. Most of the options can't be done on a laptop anyway.
You also might check New Tek's speed Edit. it is a full proffessional editing program that is in the $400 price range. I am not sure if it will work on the macbook, so check it's stats.
Mac vs. PC. The hardware installed in a mac is essentially the same as in a pc. Alienware had great support before Dell took them over and I have not had an occassion to talk to them since. We are still using our 6 year old Roswells for things like DVD duplication and a video bulletin board. We changed to Macs for Final Cut pro 4 years ago and are still using them. It comes down to operating system. Final Cut on Mac OSX is more stable on our machines than Premiere 6 was on our Roswells using XP pro, but that is kind of like comparing apples and oranges. Our macs have more power, memory and hard drive space, they are also two to four years newer, and do not have the hours of use on them that the PC's did.
Frankly I like Final Cut better than Premiere 6, but I have not seen the new version of Premiere and I hear wonderful things about it.
Tony Noon
*General Information: This is my opinion as of 12/26/07. Video technology changes daily.