When I bought my mbp 13" the guy talked me into iWork. To my surprise after a couple days of cursing I found out I really do like iWork a lot. The only problem is my school prefers Microsoft Office programs. I understand you can change the file extensions in iWork and such. But the problem I'm running into is that I need to use certain add-ins for excel (particularly Data Solver) that aren't available for Numbers. So, back to the original question. If I have both Microsoft Office AND Apple's iWork on my mbp 13", will it slow it down a lot?