If possible, put a fan in front of the hdd to blow air on it - that'll improve circulation. Basically, put the drive wherever air flows and doesn't block airflow to the rest of the system. (BTW - I've never paid more than $50 for a case - but I've always been into cheap)
120gig SATA or 160gig PATA? Tough choice. If the price & capacity were almost the same, I'd say get SATA (even pay a couple $ more for SATA but probably not $10+), but that's a tough one...
Ultra ATA/100 = market-speak for the almost fastest PATA interface available (fyi, SATA = ATA/150 but in either case, no 7200rpm drive can use all the bandwidth of ATA/100, let alone ATA/150, except in short, small bursts from cache)
That's odd re: warrantees - most of the Seagates I've seen recently all had 5yr. In any case, all 3 of those drives should be the same technology, same platter density (the 160gig uses 1 add'l platter - or 1 more side of an already existing platter than the 120gig), same spindle motor, same... etc., with possible differences being firmware. So IMO, price/gig and offerred warrantee are probably the only considerations.
Mike.
<font color=blue>Outside of a dog, a book is man's best friend. Inside the dog its too dark to read.
-- Groucho Marx</font color=blue>