DOS attacks in my router log

[chimpy]

I noticed a few days ago I have alot of DOS attacks in my router logs, now I have only just found out that the router has logs so I do not know how long this has been going on for.

This is the list after only booting up for a few seconds right now.

Destination:90.206.105.19,51515 - [DOS]

Fri, 2010-04-30 20:59:50 - UDP Packet - Source:188.246.57.44,23754 Destination:(my ip),27302 - [DOS]

Fri, 2010-04-30 20:59:51 - UDP Packet - Source:122.95.163.158,41555 Destination:(my ip),51515 - [DOS]

Fri, 2010-04-30 20:59:55 - UDP Packet - Source:125.25.11.66,15332 Destination:(my ip),51515 - [DOS]

Fri, 2010-04-30 20:59:55 - UDP Packet - Source:99.252.139.250,39298 Destination:(my ip)27302 - [DOS]

Fri, 2010-04-30 21:00:43 - UDP Packet - Source:174.58.29.165,60036 Destination:(my ip),27302 - [DOS]

Fri, 2010-04-30 21:00:43 - UDP Packet - Source:68.34.134.24,31549 Destination:(my ip),27302 - [DOS]

Fri, 2010-04-30 21:00:43 - UDP Packet - Source:173.17.210.154,19380 Destination:(my ip),27302 - [DOS]

Fri, 2010-04-30 21:00:44 - UDP Packet - Source:125.25.11.66,15332 Destination:(my ip),51515 - [DOS]

I know little about DOS attacks but I think I am right in saying that as my log shows them it means they were blocked?

What is all this about and how can I stop it?

Thanks.

Edited to say I have a black netgear router from my IPS who is sky, apart from that I do don't know much about it.