Can someone comment on the use of SSIs? Do these place a lot of strain on the server? Also, are "virtual" includes or "file" include directives more efficient?
Not much strain on the server at all. virtual might be a little more processor cycles than file, but i would definitely go with virtual - it can then be included anywhere (if you include from the webroot/slash). The processor difference is barely noticable.
Without the use of includes the use of ASP becomes very limited. It's pritty vital for storing libraries of functions and other common elements (like page header).
U r right CCOOEN it is better to work with virtua instead of file...but while making that u should knw whether ur IIS serve has support for that..