DSLR vs Micro Four Thirds
I really like the D5000. It's one of my favorite entry-level digital SLRs at the moment. Here's my pro review:
Nikon D5000 Pro Review >>
The main benefits over a Micro Four Thirds camera are better auto focus, TTL viewfinder, better low light image quality. But even though it's a small digital SLR, it's still much larger and heavier than the Olympus E-PL1.
So why would you want a digital SLR over a Micro Four Thirds camera? What is it you think the Micro Four Thirds won't do?