Using automated Tools it is not a tough task. The Upgrade Wizard in VS2005 and Vs2008 did a good job, but this tool is not available in VS 2010 or VS 2010 Express. So you can get the
Visual Basic Upgrade Companion from: http://msdn.microsoft.com/en-us/vbasic/ff793478

This tool has a lot of enhancenments for example:

Data type enhancements

Collections are upgraded to ArrayList or HashTable depending on their usage.
Integer to enumerate: when integers are used where an enum name is expected, The VBUC converts it to the corresponding VB6 enum field, and the maps it to the semantic equivalent in .NET.
IIF expressions: if the two expressions returned by the IIF have equivalent types, only one coercion is generated for the whole IIF invocation. Otherwise each expression is handled in the most appropriate way to make it match the expected type.
Several cases for conversions between types: objects to scalars (unboxing cases), dates vs. strings, arrays to arrays, fixed strings, octals and hexadecimals, etc.
Advanced transformations for arrays in most Dim and ReDim scenarios.
Integer data type variables can be optionally upgraded to Short or Integer depending on their arithmetical usage.
Enum Advanced conversions for:
- Enums in comparison operators.
- Enum values being transmitted as By-Ref.
- Coercions between Enums and other primitive data types.
Transformations for fixed size strings.