Ordinary PC webcam can fulfill your requirement. Register with Yahoo Message or subscribe ISP net meeting service around $20-30 per month. You can check anywhere with web browsing enabled PC like Starbucks or in the shopping arcades to see what you maid doing at home. I recommend Logitech as the quality is good for browsing and more popular.
I have notify my maid before start the setup and I will tell her where the cam this. Sometimes they still fool enough lie to you while you see them doing wrong things in front of the cam.
This is more a preventive setup rather than crime proving evidence since everything will become too late if we do nothing in ahead. Now I am using NetSee of Netvigator, Yahoo Messenger and Eyeball with 3 Webcams (USB) attached to one PC in the living room. The cost is $500 for three cameras. Please try three different brands as you may enjoys more software.