Is there anyway of getting the old pages that come up on Google Search to not be there anymore? As I don't like having non-existant pages in google.
Normaly Google removes old pages automaticly. But you can do it also manualy. Just ask google: http://www.google.com/support/webmasters/bin/answer.py?answer=35301
You can try all of that and google may or may not comply. I've had pages removed and then had them reappear over a year later. I've also got pages that google simply refuses to remove from their cache. Those pages haven't been on any of my sites for almost 18 months. They're deleted from the server and yet google keeps right on creating 404s by sending traffic to them. So Good Luck is what I'm saying. In the end google is gonna do whatever they want with your pages.
i would recommend putting up a page with an error like "Page not found, will redirect to main page for related articles" or something along those lines. Who knows it might just lead to some extra sales! i believe it can easibly be done trough htaccess
What like a custom Error 404 page? I would do it through .htaccess, but I didn't think spiders would pick that up?
If it's unexisted, and google will report 404 error, and about one or two month, if it's still 404 error, google will automatically remove it.
You can also set a 301 redirect to an existing page. If you want to remove it set up a 410 (gone) status code