I have macbook pro core2duo 2.8ghz, 8gb ram and adobe premiere CS6, I tried editing native DSLR footage, playback is smooth but lags when scrubbing footage, Transcoding 1080p to DV 720x480 24p, 1minute footage took 1:40 minutes to convert. what do you think is the best solution so that I can use this laptop for SDE?

Have you run a test with pro res and FCP? It might not be your NLE of choice but it would be playing to your core2duo MBPs strengths. Otherwise I think that hardware has a massive chance of letting you down under the pressure of a SDE.