I like Ginobili and all but if the Spurs did sign Arenas now then they are guaranteed to have some talent for the next 6 years or so coming out of this summer. The Spurs could 'save' some of their cap flexibility for 2004 and Ginobili could decide to tango with another franchise anyways. If Arenas is ready to sign on the dotted line with the Spurs you do that and go from here.
The #s I've seen for Nesterovic ($8 mil starting?) are excessive for his level of talent. At that price I'd rather they start Rose, sign Arenas, sign a couple of veteran bigmen for the bench, and 'save' that caproom for the people's hero Manu.
And then there's always Odom...