pentium D is dual core. it's the first of the dual-core desktop CPUs from intel, but the last of the old netburst microarchitecture. intel's naming convention switched during pentium D, which is why it might be confusing...
Pentium D 800 & 900 series AKA "Core Duo": dual core, netburst microarchitecture
"Core 2 Duo" (no "Pentium-" name): dual core, conroe AKA "Core" microarchitecture
i'd love to upgrade my workstation to 2gb ram, not for gaming purposes though. but im unfortunately still on P4/revB using DDR, which uncannily has yet to drop in price. as it is, 1gb of DDR2 ram is up to US$30 cheaper than a 1gb DDR chip...
-edit-
as for the hard drive discussion, i've had three drives fail on me so far: my first, a circa 2000 Maxtor 40gb which would get profusely hot, and considering it was my first self-built system, i had inadequate cooling to compensate. my second was an OEM WD that came in a LaCie external HDD, which was also inadequately cooled (but not my fault), and in similar fashioned gave up the ghost. my third now, which has actually come back into operation (though i suspect i should go ahead and back up the data and replace it), is actually a cheap refurb drive i got off of woot--and for that reason i expect it to perform like one.
none of my other 10 hdds (almost all WD) are giving me any problems. in my opinion, every hard drive will eventually die, regardless of the manufacturer. WD drives tend to generate less heat, so while it doesn't necessarily mean prolonged lifespan, it does give me one less thing to worry about.