All my experience is with the windows platform but I continually hear that being on a Linux box is better for search engine results. What factors should I be concerned with when choosing the platform for my website.
I was told that htaccess is a must for a good google ranking. Pages that pass variables must be renamed with htaccess to a simple html title to have good results with Google. As far as I know this can only be done with Linux.
I host a number of number of sites on shared hosting that do great in the search engines. If you can get a dedicated IP though that's the way to go in my opinion. There can be some potential downsides with shared hosting/ip....although 9 times out of 10 it's nothing to worry about.
Easiest and most SEO effective, is Apache on any platform with mod_rewrite. The rewrite modult to IIS is very expencive and cannot really produce the same result as mod_rewrite... (Time is money)
What do you mean that there are some downsides regarding the SEO results when using shared web hosting
Never experienced any personally but have read theories that having your site on a shared IP with sites that get themselves in trouble with the SE's (banned/manually removed), could lead to trouble for your site. Again, never had it happen to any of my sites. Just throwing out the theory for consideration.