Blender 2.56 is really good, you should make the move.
Some hints:
When opening old files, make sure load ui is turned off in the file options.
If your file is broken or wont open, use File Append then load your scene.
If this Fails, then try to Append the mesh, if this fails…
Don’t expect everything to be the same, it’s better!
Take the time to Explore the interface.
Especially look in User Preferences>Addons. There’s some handy tools in there.
If you don’t Build blender yourself, look to Graphicall you will be able to get builds as recent as 24hours old for most os. Most time the builds are from 1 to 12 hours old.
The Builds that say BF Trunk are the standard builds.
If you choose, you can, as I do, download special builds that contain patches or extras.
Be careful here, some builds are very experimental.
However, builds that are optimized, generally are as stable as the trunk build.
Often these are the best.
Currently I’m using Blender 2.56 by Filiciss, which is by far the best Blender build ever.
I update this as often as he does & have found them to be at least as stable as Blender!
It’s up to you to find a build & stick with the builder that suits your needs.
You will get less problems this way.
btw, Blender 2.56 is as stable as Blender 2.49b is.
If anyone has any other 2.56 hints for ease of transition, let us know.
enjoy.