http://www.newegg.com/Product/Product.asp?Item=N82E16811144109
URL for the silver X-QPack, which has the most reviews.
i'm using a shorty DVD-ROM in mine, for the time being, an old Sony.
if you upgrade the power supply, you have to watch out where the cables
exit the power supply & the length of the optical drive.
the case is 13.8" long.
a typical power supply - 5.5 inches long
the Sony DRU-810A - 6.75 inches long
the Pioneer DVR-110D - 7.09 inches long
the Samsung SATA optical drive which was hard to find a month ago
but might be available now -
SH-W163 - 7.24 inches long.
anyway, i suggest getting a shorter optical drive - like the Sony 810A -
in case you get dis-satisfied with the Aspire power supply.
hope that helps !