Sigh.. the solution in http://blogs.msdn.com/stuartpa/archive/2005/07/21/441468.aspx is MUCH prettier and I am squirming a bit as I am writing this post
First of all you need to enable xp_cmdshell (which by default is disabled for a reason
reconfigure with override
Then PLEASE PLEASE set up a proxy account for xp_cmdshell with a low privilege Windows user (see BoL "sp_xp_cmdshell_proxy_account" for instructions).
The following script is not doing anything meaningful, it is just grabbing a bunch of timestamped files into a table and then I am doing a backup using the name of the last file (it was easier to setup).
This works for me because of how the files look: SamplesDB_20081029184501.trn, you might have to be little bit more clever than me to be absolutely positive that you are indeed grabbing the last file
MCITP | MCT