[R-sig-hpc] Parallel operations

[Bill Smith]

I have a Windows box set up with two 64 bit Intel Xeon X5680 3.33 GHz processors (6 cores each) and 12 GB of RAM. I want to use it to perform matrix operations (multiplication, inversion) on some data set sets that range from 5-50 GB.  I looked around on the web, including the CRAN HPC, to see what was available. A couple of things came up, pbdr (http://r-pbd.org/) and HIPLAR (http://hiplar.org/hiplar-b.html).  Which of these is the best for my application?  It's not even clear HIPLAR will work in a Windows environment.  If I go the HIPLAR route, which of the two programs, HIPLARb or HIPLARM, is preferable?  It's not clear to me the difference in the two programs.  My matrices have a lot of zeros, but the HIPLAR software requires PLASMA/MAGMA which seems to only work with dense matrices.  Can someone help me sort this out?
 
A related question concerns the availability of an R package to perform stepwise logistic regression (yes, I know this is an unpardonable sin-I'm replicating someone else's analysis) in a parallel environment.  I believe this has been implemented in Revolution R, but I'm not sure if anywhere else.  Any guidance appreciated.