RSS does not have any inherent ordering capabilities in the specification, just because you put items into a feed in a specific order does not mean they will come out that way after being processed by our (or any other) aggregator...

There are three ways to get around this.

1.       Use publish dates in the RSS feed.

By default, most aggregators order items in a feed by the published date, with the most recent content presented first.
Note that badly formatted pubdates can be just as bad as not having a pubdate. We try very hard to parse pubdates, but if we can't parse your pubdate we will ignore it. To be safe you should try to conform to a published standard such as ISO 8601.

2.       Use  Simple List Extensions (SLE) in the feed to create what is known as a “list feed”.

NewsGator supports Microsoft’s SLE extensions to the RSS spec.  This is used to create a feed that acts like an ordered list of posts.  Posts can be moved to different spots in the list (think of a billboard top 40 music feed).

For more detail: http://blogs.msdn.com/rssteam/archive/2006/03/29/564154.aspx

3.       Use NewsGator’s “Manage Posts” feature in Editor’s Desk to order content within Editor’s Desk. Administrators can order posts manually using the “handpicked articles” feature within the Manage Posts utility.