The only requierment to use TiltViewer is Flash Player 9. Here's the v9 flash player compatibility list
Windows :
*Microsoft® Windows® Vista : Microsoft Internet Explorer 7, Firefox 2.0, AOL 9
*Microsoft Windows XP : Microsoft Internet Explorer version 6.0 ou ultérieure, Firefox 1.x, Firefox 2.x, Mozilla version 1.x or more, Netscape version 7.x or more, AOL 9, Opera version 7.11 or more
*Windows Server® 2003 Microsoft Internet Explorer version 6.0 or more, Firefox 1.x, Firefox 2.x
*Windows 2000 Microsoft Internet Explorer 5.x, Firefox 1.x, Firefox 2.x, Mozilla 1.x, Netscape version 7.x or more, AOL 9, Opera version 7.11 or more
*Windows Me Microsoft Internet Explorer 5.5, Firefox 1.x, Mozilla 1.x, Netscape version 7.x or more, AOL 9, Opera version 7.11 or more
*Windows 98 Microsoft Internet Explorer version 6.0 ou ultérieure, Firefox 1.x, Mozilla 1.x, Netscape version 7.x ou ultérieure, Opera version 7.11 or more
Mac :
*Mac OS X v.10.1 or more(PowerPC) : Firefox 1.x, Mozilla 1.x, Netscape version 7.x or more, AOL pour Mac OS X, Opera 6, Safari version 1.x or more
*Mac OS X v.10.4.x ou ultérieur (Intel) : Firefox version 1.5.0.3 or more, Opera 6, Safari version 2.x or more.
I'm not going to check if this list is 100% acurate, but i tryied different setups. Here's the list of my "working fine" setups :
* XP && IE6 or IE7
* Vista && IE7 or firefox 2
* Mac OS X && firefox 2
* Leopard && firefox 2 or the latest Safari
Anyway, you shouldnt worry too much...who the hell use safari or IE6 ? :)