Guys - I need some help. I'm doing a RTW trip with a RTW ticket and will be leaving from South Africa to Hong Kong around July 15. I only want to spend a few days in Hong Kong and then go to Malasia.

On about August 13 I want to fly back to Hong Kong en route to Beijing for the Olympics and stay in China for about 45 days.

Is there any kind of Visa I can get that allows for re-entry into China and a trip of that length? I'm worried that that short stop in Hong Kong on my way to Malasia may ruin my visa for the rest of the China trip. Many thanks for any advice!!!

You're in luck. Mainland China and Hong Kong operate under totally different visa rules. US citizens are allowed to enter Hong Kong for up to 90 days without a pre-approved visa. See the following web page:
http://www.china-embassy.org/eng/hzqz/xgqz/t84250.htm

You will only have to apply for a visa to enter mainland china. The regular Tourist visa allows a stay for up to 30 days, which may be extended for another 30 days at the discretion of the visa officer. The extension is the only dicey part I forsee. Here's the link for the China tourist visa information:

http://www.china-embassy.org/eng/hzqz/zgqz/t84246.htm

You might want to call the Embassy in Washington DC directly to ask about the 30 day extension just to make sure it'll all work out.

Pete - thank you! That makes things SO MUCH easier!!! I assume I can get a visa for China in Hong Kong or Indonesia without much trouble? Thanks again!!!

Very easy to get your visa in Hong Kong, either through an agent or through the visa office in Wanchai. if you pay extra you can get it in a day, although as you will be in HK in July for a few days, you might as well get it then.

If you haven't already booked your air tickets in China, it is usually much cheaper to fly from Shenzhen (next to Hong Kong but in Mainland China) to Beijing than from Hong Kong.

If you do decide to go by train and then taxi to Shenzhen airport please ensure you don't get an illegal taxi at Shenzhen station. Recently there has being a spate of robberies where travellers looking for a deal get in any old taxi and get taken to a remote part of town and robbed of all their possensions. Make sure you join the taxi queue (which is sometimes quite long) at the official taxi rank (you will be fine then).

See my other post about getting the ferry to Shenzhen.

Depends how much you want to spend.
You can get airport express train to Hong Kong central (HKD100) then get ferry to Shenzhen airport (ferry port is called FuYong -dont go to SheKou) (HKD249 I think). This quite easy to do.
There is now also a bus service from HKIA to Shenzhen airport but I dont know details for it. It shouldnt be hard to do this as the busses leave from terminal 1 at the airport which is where a majority of flights come in (Term 2 is across the railway so it is not huge deal.