I am not aware of anything stop you loading up Office 98 to Office 2007 on a new computer. You simply stick the discs in the drive and click install. I am still using Office 2003 I simply do not need the new features. As to Outlook Express that was part of operating system think Windows 98SE was last to include it today we have Windows Mail which is similar.
In theroy you should un-install from old computer first but with CD's there is really no problem not sure about floppies I know some programs you had to un-install with floppies in drive before you could re-install to another computer.
Where original disks have been misplaced think you stuck. I know with Nokia phones you did get Excel free but latter phones you had to pay and there was no way to transfer licence to new phone. I spent ages rewriting the spread sheets I had in Java Script so I could run them on a browser.
Open Office does not have something like Outlook at one point there were many email packages but today we tend to read on line rather than install a package.