How do I keep Books & Spoken off randon playlist of library?

You will have to modify your playlist to exclude the genre 'Books & Spoken'. Are you new to iTunes? The reason I ask is because this is your first post.

933 MHz iBook G4 Mac OS X (10.4.5) 640MB RAM, AirPort Extreme

"Smart Playlists" are playlists that are automatically updated based on criteria you set and the number of songs/audiobooks/etc. that can go in these playlists can be from 0 to your entire library. "Playlists" are playlists that have to be manually populated by dragging items into it from the main library or another playlist. Both types of playlists have their advantages and disadvantages so how you plan on using the playlist will determine which type to use.

To create a smart playlist that does not contain 'Books & Spoken' you need to go to File -> New Smart Playlist. A window will appear where you set the criteria. In first list box select 'Genre', in the second list box select 'Is Not', and in the third type 'Books & Spoken'.

If you want to use criteria such as 'Kind', 'Last Played' but you do not know their values then go to Edit -> View Options... and select the criteria you want to use. With the exception of 'Name' (of the song) you can rearrange the order columns are shown. Apple has tutorials on their web site and if you select on the following link it will take you to one that shows you how to create smart playlists.

http://www.apple.com/ilife/tutorials/itunes/it2-2.html

933 MHz iBook G4 Mac OS X (10.4.5) 640MB RAM, AirPort Extreme

The 'Limit to' check box is used to limit included, not excluded, content that will go into the smart playlist.

The 'Match only checked songs' is used to keep songs that are in iTunes from getting included in the smart playlist. If you have a song that you do not want to hear because:

1 - you have heard it too many times
2 - it was the song that was playing when you got dumped
3 - etc.

then check this box and uncheck the song and it will not get included in the playlist.

The 'Live updating' checkbox, when checked, will update the playlist whenever changes are made to criteria you have set for that playlist.

You can drag the 30 second previews from the iTunes Music Store into a non-smart playlist, so if you are going to purchase content I suggest you create a playlist for this purpose. There are a few advantages to doing this and they are:

1 - The playlist can be used as a "wish list" of songs you want to purchase. This is really nice for songs that pop into your head when you aren't buying songs, but stay on the tip of your tongue when you are buying music.
2 - You can listen to the 30 second previews and buy the songs while in the playlist so you do not have to go to the iTunes Music Store. Plus, with all the songs you want to buy in one list it makes it easier to decide which one(s) you want to buy first. After you buy the song the 'Buy Song' button disappears so you do not accidentally buy it a second time.
3 - I have not done it, but I believe you can load the playlist onto the iPod so you can listen to all your previews.