All Scripts/General
When I load up somefile.php I see raw PHP code/a load of gibberish
Chances are that PHP isn't installed and configured as expected. Contact your server administrator and ask them if your server supports PHP and, if so, what file extension your server uses. If this is not .php then rename setup.php with the required extension.

Banner Exchange
How many impressions can the Banner Exchange handle?
This is a difficult question to answer, as it depends on many factors including server specification, size of database and luck (ie is a suitable member found quickly). What I can do, is give you examples of high usage.

We were able to verify that a real exchange running on an $85/year shared server with PHP3 was able to serve over 250,000 in one day when a member was abusing the service. It is unlikely that this user was loading adverts all day, so the rate probably exceeded 500,000/day at some points. At the time they had a database of about 200 members. The user was abusing the exchange over a period of several days, and at no point was the exchange webmaster contacted by their webhost, so server load cannot have been too high. Remember that PHP4 with PHP optimizer installed is many times faster than PHP3.

Another commercial exchange has reported nearly 2 million impressions per day with no problems, on a database of over 25,000 members. Although we have not been able to verify these statistics, we have no reason to disbelieve them

A third exchange, running on two servers, has been able to easily server 1 million impressions per day. The server administrator thinks this configuration would be able to cope with 50 million impressions per day. This exchange was previously running WebAdverts on the same servers, which was causing regular data corruption because of the high load. To put this in perspective, the author of BannerPlus, a banner exchange written in Perl says "It has been reported to me by customers that [BannerPlus] works OK with 100,000 hits per day. It is not recommended for volumes significantly in excess of this figure".

MySQL
I run my own server and I don't have MySQL installed. Is it expensive?
No, MySQL is free for use with the QAlantis scripts. Full details of the MySQL licence are available in the MySQL manual. MySQL is released under the GPL (General Public License) meaning it is open source software.

I rent a virtual server from a hosting company, will MySQL increase the cost?
Your server may already support MySQL, check with your hosting company. If it does not, then there are lots of budget hosts offering MySQL and your existing host may offer a different package with PHP and MySQL support.

I have not heard of MySQL, is it in use on any large websites?
Yes, a number of large websites use MySQL, including Yahoo!, TuCows and Slashdot.
A more complete list can be found at the official MySQL website.

PHP
I run my own server and I don't have PHP installed. Is it expensive?
No, PHP is free for everybody. It was originally released under the GPL (General Public License), but this was thought to be too restrictive so it is now distrubuted under the PHP & Zend licences. PHP is open source software, for furthur details please see the PHP 4.0 License FAQ on PHP.net

I rent a virtual server from a hosting company, will PHP increase the cost?
Your server may already support PHP, check with your hosting company. If it does not, then there are lots of budget hosts offering PHP and your existing host may offer a different package with PHP and MySQL support.

I have not heard of PHP, is it in use on any large websites?
PHP is already a major platform for websites of small to medium sized businesses, but is also used by a growing number of enterprise-size organisations. All links below are to pages using PHP or directly linking to pages using PHP.

Zend's customers, and therefore PHP users, include: Hewlett Packard, wallstreet:online, Lucent Technologies, Avaya, Sprint, Nortel Networks, Epiware, Lufthansa, AMJ technologies, Bausch&Lomb, SportMart, webMethods, Lycos, Alstom, Terravista CMG, Teradyne, Intellisource, ITG, Niagara Mohawk, Siemens, McGraw-Hill, MCS Cityline, US Bureau of Land Management, Outback Steakhouse, Perry's Ice Cream, Ensim, Deutsche Telecom, Apple, McGraw Hill, CBS, BAE, Vivendi, Lucent, WestLB, Motorola, GlobalScape, ZiffDavis, eSoft, Sphera, WebFactory, NTT, ADC, Zuchetti, CMG, GlobalScape, Deutsche Bank, Dresner Bank, US General Accounting Office, Geogia Tech, Noggin, DMC, Bravenet, AuctionWatch, OnVista, Ananova / Orange, Maxis (Sim City), AMD, Linux Journal and over 100 universities worldwide.

Badblue lists the following companies as users of PHP: CapitalOne, NASA, the W3C, Google, Redhat, Cisco, Ericsson, Volvo, SourceForge, Honda, WinAmp & Shoutcast, Sony Music, Vodafone, Cap Gemini Ernst & Young, the US Army, UPI, the New York Yankees, Southwestern Bell, the San Diego Zoo, the Oakland Raiders, Audi, Subaru, VA Linux, Quicken, The Village Voice, Undernet, Access Micro, Columbus Dispatch, Indianapolis Star, Central Scotland Police, University of Portsmouth Unilever, Philips, BMC, Air Canada, Dialpad, BMC, Mitsubishi, Bang & Olufsen, MP3.com, the Arizona Republic, Deloitte Consulting.