However, as I need other osgeo4w packages as well as features in the 'unstable' release (unstable is somewhat of a misnomer, as I understand, really is just shorthand for saying it has features that aren't fully supported as in the 1.x version), I wanted to install with the osgeo4w package. For some reason osgeo4w crashes when I try to use the express install option, though I needed to use the advanced install anyway in order to get unstable qgis.
Steps for this are as follows
- download osgeo4w from http://trac.osgeo.org/osgeo4w/
- open installer, select advanced install
- select the following packages to install: qgis (unstable if you want, which was 1.4 at the time I wrote this), qt4-libs, libpq, zlib, geos, gdal16, ogdi, expat, proj (you will need to rename, read this), xerces-c, hdf4, hdf5, libjpeg,libgeotiff,libpng,libtiff, netcdf,libjpeg12, sqllite3, tcltk, zlib1 (install zlib and make a duplicate renamed to zlib1.dll), curl, iconv, sip, pyqt4,