You're not fast enough to get any accepted shares. Sorry, try an alt coin like litecoin instead. Burnside is a good pool for litecoin.
Ditto. Slush's pool will reject any shares from the previous block when a new one starts, and your 5 MH/s doesn't seem to be capable of submitting one in time. If you're really dedicated, you can try a pay-per-share pool like BTCGuild, which will pay out to any shares submitted. Most of your shares will make it, but you'll still have pretty meagre rates.