Laptop Cooling Pad

I'm using a laptop-sized, vented, inverted vegetable tray to keep the laptop cool. It's quite effective even without any fans in this scorching heat. I added a CPU fan underneath ( 12 V, 0.42 A), and ran it off a USB cable from the laptop.

The air is quite nice, but one thing I'm a bit worried is, when I touch the top of the laptop, it slightly vibrates constantly due to the fan underneath. Is that dangerous for the laptop? I'm planning to add another fan beneath the hard disk. The one I have now, is under the laptop's CPU fan.

Another thing I would like to know is that, is it okay to run two fans of 042 A each, from two USB ports? Each USB port can supply 0.5 A max current. Running one fan off each port should be okay?

But, today, the temperature was quite high in the afternoon, nearly 50 degrees! I'm thinking of buyin a readymade laptop cooler.  One of these three cheap ones at ebay India:

http://cgi.ebay.in/Folding-Chill-Pad-Stand-Laptop-Cooler-Cooling-2-Fan-/250631119144?cmd=ViewItem&pt=LH_DefaultDomain_203&hash=item3a5ac76128

http://cgi.ebay.in/Chill-Pad-Stand-Laptop-Cooler-3-Fans-USB-Fan-LED-Light-/250629679857?cmd=ViewItem&pt=LH_DefaultDomain_203&hash=item3a5ab16af1#shId

http://cgi.ebay.in/New-Super-Mini-2-Fan-Foldable-Laptop-Cooling-Cooler-Pad-/280504780978?cmd=ViewItem&pt=LH_DefaultDomain_203&hash=item414f6348b2

Please advise / comment.

Regards,
RS