csv to xls / xls to csv converter

We need a program, which can be executed from PHP script with 'exec' command. The program should be able: - to convert CSV file into Excel .xls file. - to convert Excel .xls file into CSV file. For example: [login to view URL] "path/[login to view URL]" "path/[login to view URL]" or [login to view URL] "path/[login to view URL]" "path/[login to view URL]" .xls files should be compatible with MS Excel versions from Office 97 and newer. converter should work properly with different character sets (especially Polish characters - Windows-1250). The program has to be stable and should not consume too much server resources. It should work with files up to 50MB. In case when something is wrong with the file, it should report some errors and cannot crash the server. If the program would require commercial library, please give me details how much the royalty free license costs. Other proposals which allow me to create .xls files from PHP application (both on Windows and Linux) will be considered. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform Must work on both Linux and Windows platform (XP, Vista, Windows 2000) Apache 2.x, PHP 5.x. May require Java Environment. Cannot require .net,.asp, visual basic etc.