How to get a post content from another wordpress blog/site?

I have a situation where i need to display posts from a specific category from another wordpress site into my wordpress site.

Both are my sites and i thought of creating a page specially for this in site A and calling them through iframe in site B.

I thought another way of fetching them feed.. But i dont know how to fetch feed contents from other wordpress and how to create a feed for a specific category.

Instead of parsing the RSS feed, you could query the second blog directly with the builtin XML-RPC webservices, described in this Question.