IPAcco should work on any system (Windows, Linux, Unix), provided the following components are available:

1. PHP-compatible Web-server. Apache and IIS would definitely work and probably many others will work too.
2. PHP server-side scripting engine version 4.3.2 or better. I tested IPAcco with PHP 4.3.4 through 4.4.0 and 5.05 (since IPAcco release 0.2.0.1). If you have not PHP you may get it from www.php.net.
3. MySQL database server version 4.x or better with InnoDB support. I tested IPAcco with MySQL 4.0.15, 4.0.17, 4.1.7 and 4.1.14. InnoDB is required because the script that downloads data from the router to the database, which is a part of IPAcco package, makes intensive use of transactions when it repacks data from "Day" tables to "Week" ones, from "Week" to "Month" and so on. Probably any MySQL storage engine that support transactions (i.e. BDB and NDB) would work, but I tested IPAcco with InnoDB only. MyISAM definitely will not work. MySQL can be obtained from www.mysql.com.
4. TCL scripting language interpreter with "mysqltcl" package installed (MySQL client driver for TCL) for data collection (i.e. downloading from the router to the database). I don't know exactly what TCL and mysqltcl versions are and what are not compatible with IPAcco. I tested IPAcco with TCL 8.3.5 under Linux, ActiveState ActiveTCL 8.4.5 through 8.4.9 under Windows and with mysqltcl 2.50 under both systems. You may get TCL from www.activestate.com or from www.tcl.tk and mysqltcl from www.xdobry.de/mysqltcl.
5. "rsh" command available on the same machine as TCL and mysqltcl. This command is a part of RCMD, a classic Unix remote access protocol (Remote CoMmanD). It naturally presents in all Unix/Linux systems and also in systems based on Windows NT, i.e. Windows NT itself, Windows 2000 and Windows XP. Unfortunately, there is not "rsh" command in Windows 9x, so such systems cannot be used for data collection.
6. A good CSS-capable GUI web-browser for data observation and analysis. Java support is not required and requirements for Javascript support are so minimalistic that virtually any modern GUI browser will suffice. But a good-quality HTML and CSS rendering capability is highly recommended. I prefer Internet Explorer and Mozilla Firefox, but you may try a browser of your choice in hope that it will not cripple IPAcco output too bad. :-)
7. An IP accounting-capable router itself. All Cisco routers and IOS versions I know support IP-accounting.