Good point. IDE drives came in ATA/33, /66, /100, /133. Not 150 or 300 - those numbers are associated with first-generation SATA and SATA II. So make sure what ports you have.
The board is from Abit, not ASUS. See here:http://www.abit.com.tw/page/en/motherboard/motherboard_detail.php?pMODEL_NAME=TH7II&fMTYPE=Socket%20478&pPRODINFO=Specifications&fSEARCHTEXT=TH7II
The specs clearly say it has two IDE ports supporting up to 4 ATA100 devices, but no mention of SATA. How many are in there already? Space to connect one more? Review how to set Master and Slave jumpers and connect data ribbon cables. Make sure you check whether this board's BIOS supports "48-bit LBA" necessary to use HDD's over 137 GB.
Be aware I believe Abit got out of the mobo business, although they are still operating in many other products and their website for support works. Just not sure how much more support they can provide beyond the website.