Best environment to develop multiplatform application

desktop and web based...

[Algebrator]

I appologize in advance for this topic not being 100% on the subject, but this forum is the closest fit.

I am about to start rewriting a 'legacy' application (written in Pascal , 10 years ago) in one of the current programming environments. Beside expanding the software's capabilities, the main reason for this is making it run on platforms other than Windows (i.e. Mac, PDAs etc.) and as a (subscription based) web application. The application is a pretty complex one (70K lines of pretty tight code). The languages that I am considering are C/C++ and Java, and particular environments that I briefly looked at are MS visual C++, C#, Borland's JB and QT C++ environment.
While this is primary a desktop application, I would ideally like to choose a language / environment that will be most "web friendly" once I decide to make this a web application. I am moderately experienced in C/C++ and Java but I will have to go through a pretty steep learning curve to redevelop an application of this size no matter which language I decide to go with. I have also written simple applets, but have no idea what kinds of issues I will be facing once I try to develop a large web based application. Any advice will be greatly appreciated.

Off the topic, does anyone know of good "software developer's forum" (as good for general software development as WebmasterWorld is for web related subjects)?

[bcolflesh]

Out of the technologies you mention, JAVA will be the easiest to port/maintain on various platforms. You can use JSP to "webify" it when you are ready.

[Algebrator]

If I go that route, am I losing out as far as efficiency of desktop app.? I know that theoretically this will be a compiled code (via JIT), just as good as C++, but am hearing that many developers are not satisified with the overall 'responsivness' of a stand alone JAVA app.

[bcolflesh]

Depends on your target platform specs - .NET derived C++ apps will always run faster in Windows, unless you are the worst programmer ever ;)

[Algebrator]

I expect that even after making the software available on multiple platforms, more than 70% users will still be Windows based - so I have to be careful not to degrade the performance too much (by using JAVA). My guess is that 20%-30% in speed reduction would still be acceptable price to pay (in return for hassle free porting to other platforms).
Do you by any chance know of any major commercial apps written in JAVA (and running on Windows)?

[bcolflesh]

Do you by any chance know of any major commercial apps written in JAVA (and running on Windows)?

Most of the Oracle web-interface tools, as well as the GUI itself, are a mix of JAVA and JSP.

More examples here (note probable site bias):

[java.sun.com...]