[BioC] Error in RCurl and GEOquery installation

[Momin, Amin A]

When I try installing RCurl package for the installation of GEOquery in RHEL5 I get the following error.
I would be happy if some one can give me suggestion to solve this.

> install.packages("RCurl")
--- Please select a CRAN mirror for use in this session ---
Loading Tcl/Tk interface ... done
trying URL 'http://cran.hostingzero.net/src/contrib/RCurl_0.9-3.tar.gz'
Content type 'application/x-gzip' length 150822 bytes (147 Kb)
opened URL
==================================================
downloaded 147 Kb

* Installing *source* package 'RCurl' ...
checking for curl-config... no
Cannot find curl-config
ERROR: configuration failed for package 'RCurl'
** Removing '/usr/lib/R/library/RCurl'

The downloaded packages are in
        /tmp/RtmprTpHXJ/downloaded_packages
Updating HTML index of packages in '.Library'
Warning message:
In install.packages("RCurl") :
  installation of package 'RCurl' had non-zero exit status
> 



Thanks 

Amin