Here is a very simple macro that should do what you want. It'll dump the info to a CSV, then you can open it in Excel and save it as an Excel file. If there are any commas in your descriptions and/or filenames, it may take some massaging to clean it up.
There is a way to do this without opening the files, but it requires installing somet stuff, and it's a bit trickier. This macro opens the parts, but won't load them into memory.
Make sure you change the paths to what you need them to be. Also, this is currently for .SLDPRT files. If you want drawings or assemblies, you just have to change to .SLDPRT to .SLDDRW or .SLDASM.
Dim Part As SldWorks.ModelDoc2
Sub main()
Set swApp = Application.SldWorks
Set fs = CreateObject("Scripting.FileSystemObject")
Set a = fs.CreateTextFile("C:\File.csv", True)
FileName = Dir("C:\*.SLDPRT")
visibility = swApp.DocumentVisible(False, swDocPART)
a.writeline ("Part Number" & "," & "Description")
Do While FileName <> ""
Set Part = swApp.OpenDoc("C:\" & FileName, swDocPART)
Description = Part.GetCustomInfoValue("", "DESCRIPTION")
a.writeline (FileName & "," & Description)
swApp.CloseDoc FileName
FileName = Dir
Loop
visibility = swApp.DocumentVisible(True, swDocPART)
End Sub