Rosicky or Riquelme would be absolutely brilliant, but unfortunately both of them are cup-tied. Afaik David Pizarro is cup-tied as well (Udinese were in the Uefa Cup, right?) and I don't want us to sign someone inferior to these players just because we're looking for someone who is eligible for the CL. I'd sell Appiah, bring back Maresca and work from there. If Enzo can successfully take the playmaking reigns then we would save ourselves some cash. He is an excellent two-way midfielder and I see him forming a great midfield partnership with Emerson. If Maresca fails, sell Tacchinardi and go for Rosicky, Riquelme or Pizarro in the summer. Another option would be to take someone on loan as opposed to getting Maresca. If the loanee does well enough we would sign him permanently, if not we would terminate his loan contract and swoop for Ros, Riq or Piz in the summer.
A central defender is needed RIGHT NOW for sure. Chivu would be a dream signing but I don't see it happening, not now anyways. I've been following Gonzalo Rodriguez (Villareal) and Luis Perea (Atletico Madrid) as of late and like what I'm seeing, but the former wouldn't be eligible for European play. Have Atletico also participated in the Uefa Cup? I don't think so because we're being linked to Ibanez, who also plys his trade for them.
As David Del Piero has pointed out, Jorge Andrade would be a good signing. Ricardo Carvalho stole all the headlines at the Euros but his central defensive colleague was extremely sturdy as well and has been performing for Depor on a consistent basis for some time now. He's a quality player and would make a fine back-up. I'm sure he'd make a good future starter as well.