Suggested bitrate for H.264 streams

I'm currently uploading my back catalogue of work to an online portfolio for potential clients e.t.c. to view.

I've been playing around with H.264 to get the best quality vs. file size and I'm looking for some input from the pros!

From my tests, I can take the bitrate as low as 1,000kbps and still got what I'd deem to be an "acceptable" image. What are your thoughts on what would be the ideal kbps to enable streaming on a range of Broadband connections - is 1,000kbps still too high to play smoothly on a variety of connection speeds? It's vital that these clips be readily accessible for as many people as possible with a decent broadband connection. I'm using a frame size of 640x360 - which seems to work well and I need a fairly large image as many of the people viewing these will want to judge their technical quality.

Also, I'm using Compressor and working with mostly 16:9 material. Some shot on DV-PAL and some in HDV1080i. Are there any compression techniques you would recommend to help improve final output - especially with my HDV material (I'm a little unsure about what an ''ideal'' frame size would be when compressing HDV content)