Help on packages working with excell files

Dear friends,
I am trying to install and use xlsx package. After installeing xlsx and
rJava successfully, I type >library(xlsx) then R said :
"library(xlsx)
Loading required package: rJava
Error : .onLoad failed in loadNamespace() for 'rJava', details:
  call: fun(libname, pkgname)
  error: No CurrentVersion entry in Software/JavaSoft registry! Try
re-installing Java and make sure R and Java have matching architectures.
Error: package ?rJava? could not be loaded"
I did the same for gdata package,  after installing succesfully and calling
library(gdata), I did:

myDf<-read.xls("levuan2kq.xls",sheet=1,header=TRUE)

Error in findPerl(verbose = verbose) :
  perl executable not found. Use perl= argument to specify the correct path.
Error in file.exists(tfn) : invalid 'file' argument

Till now, I could not use any package to work with excel file.
Anyone can help me.
Thanks,
Tu