All the HDD makers have single platter SATA II 160GB HDDs in the market - if you decide to buy a 160GB HDD look for one from your make of choice. These single platter HDDs are very fast and they run cool.
I have 3 of Hitachi's 160GB 7K160 series HDDs and they have a data transfer speed of 65MB/s. Hitachi have in this same 7K160 series a 80GB HDD too - I think this may be the fastest 80GB available. I paid 2650/- for each of these 160GB HDDs a month back - may be a bit cheaper now.
Seagates 160GB single platter is the 7200.9 series ST3160811AS.