You didn't state your target for VBScript. There are basically five:
[ol][li]Server-side Web development - Active Server Pages
[li]Client-side web development - DHTML
[li]Advanced "productivity app" macros (Office programs)
[li]Scripting PC/network administration - .VBS, .WSF files (typically CScript)
[li]Desktop applications - .VBS, .WSF, .HTA files (usually WScript or HTAs = IE 4+)
[/ol]
For the first 2 I use/recommend Visual Studio, but then I already have it, use it for other tools as well. If you don't have it, but
do have a late version of MS Office, see:
Be sure to scroll way down the page to "Software Tools."
For the third possibility above, well Office already has it (the link above talks about using the script editor in Office for general DHTML editing).
For making .VBS and .WSH files I've looked at a few of the fancy script editors and haven't seen one yet that I liked or that was cheap enough in my opinion. Others will chime in here I'm sure.
For HTAs I'd have to say InterDev or else see that link above once again for "how to use Microsoft Script Editor" under the heading Software Tools.
New to HTAs? See:
On that page scroll down to a heading about "vbsForm."