2nd HDD mounting rack in a laptop...........?

I have an Acer Aspire 9525 laptop. It was decently-priced for the 7900gs 512MB GDDR3, Core 2 duo, 17-inch ...etc specs as opposed to other brands.

I bought it from a retailer, and whereas it is possible to order the option for a dual HDD spec, mine came with only one Hitachi 160GB SATA 5400 rpm. And now after extensive useage, it does seem to me that the HDD is the main bottleneck of the system.

So I approached the ACER official agency here, and it turns out that whereas an identical HDD (for if I wanted a RAID 0 array) costs about 110 USD to buy "outside", ACER are charging 200 USD. Furthermore, they are charging an extra 120 dollars for installing it/labor.

So I figured the difference was too great for an upgrade they won't know about anyway, being careful with unscrewing the HDD compartment as to not show any wear on the graphite screws, and installing an identical hitachi HDD, that might have been provided with purchase anyway ..etc, and I've been told that adding a second HDD doesn't void the warranty on the base system (if they figure that the second HDD isn't theirs).

However, upon opening the HDD compartment, there -indeed- was a second space, but it was plain empty black plastic, with the connectors, but no mounting rack, as opposed to the first HDD's compartment which house the original HDD in a chrome/nickel-like rack, that is screwed to the chassis.

What to do now? Where do I get a mounting rack that would fit? No one seems to sell it online.

I'll include a picture if needed, but I get the feeling you guys would know what I'm talking about. Is the rack necessary?