To upgrade your X server, the package you need is dependent on which video card you have. Get the server which matches your card.
Upgrade your X libraries and base install
rpm -Uvh ftp://updates.redhat.com/5.2/alpha/XFree86-libs-3.3.3.1-1.1.alpha.rpm
rpm -Uvh ftp://updates.redhat.com/5.2/alpha/XFree86-3.3.3.1-1.1.alpha.rpm
Optionally, upgrade the additional X packages, such as fonts, devel, etc.
Upgrade your X server. The package you need is dependent on which frame buffer your SPARC has. Get the server which matches your card.
Upgrade your X libraries and base install:
rpm -Uvh ftp://updates.redhat.com/5.2/sparc/XFree86-libs-3.3.3.1-1.1.sparc.rpm
rpm -Uvh ftp://updates.redhat.com/5.2/sparc/XFree86-3.3.3.1-1.1.sparc.rpm
Optionally, upgrade the additional X packages, such as fonts, devel, etc.
If a link named /etc/X11/X does not exist, pointing at the proper X server that you use (for instance, /usr/X11R6/bin/Xsun), create it now.
cd /etc/X11
ln -s ../../usr/X11R6/bin/Xsun ./X