In .NET 4 we have quite a few deployment options available for redistribution. There are basically 2 pivots. The Client/Full profiles and 32bit/32+64bit packages.

Here are the four redistributable options and their corresponding sizes.

Redistributable Size
32bit Client Profile 28.8 MB
32bit Full 35.3 MB
32+64bit Client Profile 41 MB
32+64bit Full 48.1 MB

The Client Profile is targeted to contain the parts of the .NET Framework that are used by most client applications and gives people the option to carry a little less payload if they use less of the Framework.

The 32+64bit packages are designed to give the option of installing either profile on any target machine regardless of OS architecture. On the other hand, if someone is targeting a pure 32bit customer segment, the 32bit package gives the option of reduced size with reduced breath of deployment.