Need you help !!!

I have a website, and desperately need a simple javascript.

Here is a requirement:

The balance of my account will appear in the web, and it's dynamically INCREASING every second at certain percentage. I expect it similar to the "counting free storage" of GOOGLE:

For example: In website

At 10:20:23 --> "your account balance is $435usd"
At 10:20:34 --> "your account balance is $435.435usd" (I assume 1/1000 increment)

Any body help me writing the script please !!!??? I think it's quite simple but I am just an novice ! #!$#@!hichic

Thanks a lot !!!