Technological choice

What is the best technological choice if one wants to redevelop his applications (Oracle 6i) using WEB technology and taking into consideration the following constraints?

? Performance is critical (real time calculation)
? Database independent
? Browser independent
? Operating system independent
? In general, platform independent.
? Scalability is a must
? 100% Web-based
? Quick programming
? Standard technology
? Popular technology
? Investment cost is limited

Please advise about:

? Server applications
? Tools
? Languages
? Principles (to ensure platforms independency)

Thanks in advance