When installing Solaris I generally prefer to do the minimal install because I don't like GBs of stuff I don't require cluttering up the system. However, you can encounter a number of problems when doing this. Not least because some important applications are *not* installed by default - such as ssh and gunzip.
gunzip is contained within the SUNWgzip package which should be on your original install CD. The following command will install it (assuming you've mounted the CD drive).
pkgadd -d /mnt/cdrom/Solaris_10/Product SUNWgzip
Before you start pulling your hair out in exasperation, you'll probably want to install the Bourne Again Shell (bash), so enter the following.
pkgadd -d /mnt/cdrom/Solaris_10/Product SUNWbash
You'll also want a copy of wget (easier than command line FTP), which you can download from ftp.sunfreeware.com. However, I found a few dependency problems with 1.11.4 so I downloaded 1.10 instead, which seems to work ok.