I am trying to import results from a Google Search results rss/xml feed into my website but every time I run the python script I get a message from Google:

Our systems have detected unusual traffic from your computer network.
  This page checks to see if it's really you sending the requests and
  not a robot.

The script uses urllib to download pages and works with other rss feeds.
Doesn't really make sense as I thought rss feeds were supposed to be consumed by software (bots), I left the script over the weekend and ran on Monday morning but still got the message so I am not hitting their servers too much.
I can load the feed in my browser though and I can also download the feed using wget on the server?
You could use some HTTP sniffer (like fiddler) or any protocol sniffer (tcpdump, wireshark) to sniff your network traffic to Google and check if your urllib request and wget/browser requests differ. Also check and compare all the cookies and HTTP-headers of both requests. And remember , that for IPs with big number of requests to Google - google sends captcha every N requests , so if you need to parse it's content - you possibly need to use some proxies for Google parsing.
How to fetch a google search results feed with a python script and not be identified as a bot?