Is there a theme that reprises the old Sun Sparc style interface?

Something like the following:

or

You want the CDE desktop environment featuring the Motif toolkit.

As an old-timer, I believe you will have no trouble installing these, even if you have to use the command line ;-).

CDE Solaris theme

GTK2-notif2, a Motif GTK+ 2 theme

Metacity Motif

The second image you showed is of OpenWindows. A similar appearance can be obtained by using OLWM or OLVWM, but you won't necessarily have the same applications. (though, the applications actually pictured are XV, Netscape, both of which aren't actually part of openwin, and shelltool, which is a fairly boring terminal emulator.)

I don't think there are any GTK/QT themes that emulate Open Look, though.

Beyond that, some applications with the same look can be found at http://step.polymtl.ca/~coyote/xview_main.html - I don't think any of them are packaged.