Keep Cassell and add Marbury. Don't let this be the jinx, but you never know when an injury to Rondo or Ray might happen. Both Cassell and Marbury could fill those voids as starters or 2nd unit. Here would be my ideal active roster for the Playoffs
Rondo, Marbury, Cassell
Ray, House
Pierce, Sefelosha(Trade Tony Allen)or Damien Wilkins**
KG, BBD(or Powe)
Perk, Scal, Pat0(or Joe Smith if we got him)
**Convince OKC to buyout Joe Smith(take a paycut) and trade Tony Allen and Powe or BBD for Damien Wilkins. Trade machine works out. We get our old vet big man with offense good rebounding, we get rid of the Small PF log jam, and we get a SF w/ 3point range and length(and he can run the point!)