I'm currently using default implementation of STL for VS2005 and I'm not really satisfied with it. Perhaps there is something better?
Dinkumware supposedly produces one of the most standards-compliant implementations of the C++ standard library. You can get a binary licence for VS2005 for $200.
The Dinkumware STL implementation (supplied with VS2005) is actually quite good. The STL is a general purpose library and so it is almost always possible to write something better for very specific use cases.
I'm aware of the following alternative implementations, but I've never used them with VS2005:
SGI Standard Template Library 3.3: http://www.sgi.com/tech/stl/
STLport 5.1.6 (derived from SGI implementation): http://www.stlport.org/
Both SGI and STLport implement the size/length check as the first test in operator== and so you might like it. They are also both free to download and use.
Changing from one STL implementation to another, in theory, should be easy. However, I've heard from some colleagues that it is not always so. They've tripped over compiler bugs, found that they've inadvertently used non-standard features, or unknowingly relied on some behaviour specific to a particular STL implementation.
One good thing about the Dinkumware STL implementation is that it has been well tested with the VS2005 C++ compiler.
If you decide to try out these alternatives, good luck! And let us know how it goes.
There is also Apache STL, but as others have noted, I believe Dinkumware is your best bet.