To be honest, as far ATS plays go, Boston as an underdog is most likely the best value on tonight's NBA card. Pierce and Allen have been obviously stepping up more than usual on both ends of the floor since Garnett went down, and those two will be assigned to defending Wade more than likely. Boston won't have to worry too much about Miami's big men, which would be why Garnett wouldn't be missed as much like for instance against Orlando.
Look at the games they have lost since Garnett went down, mostly teams with a good PF/C combination. Randolf and Camby exploded on them when they played the Clips...
Couple the fact that Boston are on 2 days rest, which is the optimal rest time (enough rest without rust being a factor in the 1st half)... and Miami coming off a double overtime, and you could almost say... a delusional win against Chicago who are putrid on the road. Coming off a win is usually a disadvantage, but coming off a 2OT win like that should be even more so...
Rondo being out will be a factor...but this might be the first game they realize Marbury is a cancer and he'll be lucky to get even 10 minutes of playing time, which will be an added bonus for Boston. They also know better than any other team how to defend a one man show (Lebron for instance). If you do make an all nothing bet like this, its good to do with a team that is really battling for the first seed, hobbled or not.. and have them as an underdog to boot....
But, I really hope you reconsider your options and finding a better way to get through the situation your in....