Checking this out myself... Immediate impressions include the fact that it has a quarter the expansion of dualie macs (in RAM) and half of the single's (the HP has only 2 slots), no digital audio, no standard SATA...
AMD Athlon F64 3200+
Windows XP Pro
256MB PC3200
160GB SATA RAID (only SATA option)
4x DVD+RW/+R
2 USB 2.0 + 1 Firewire 400 + WinDVD
No floppy
128MB GeforceFX 5200XT
Soundblaster Audigy 2
No monitor
Microsoft Works 2004 (MS Works, Money, Encarta, Word)
Norton Antivirus 2004 (1 year subscription)
Total: $1,204
Cons: MicroATX! (low expandability), one firewire 400 port on front and back, one hard drive bay, two PCI slots open (no PCI X), 2 RAM slots, no gigabit ethernet, no iLife, no Panther.
I ran the parts on that, building it yourself, and it would cost around $900 for the cheapest components available, maybe a shade less if you caught specials or waited a little longer. There's no way they're making any money at all on those things, unless they've got some ridiculous cut rate on their supplies (something Apple doesn't have)
A more comparable machine looks something like this:
Intel Pentium 4 3ghz
Windows XP Pro with Plus! Digital Media Edition
256 MB PC3200 RAM
GeForce FX 5200 128MB (the new card, apparently)
Dell Optical Mouse
8x DVD+RW/+R with MyDVD Deluxe and RecordNow! Deluxe
120GB SATA
McAffee Security Center (virus, firewall, privacy for 1 year)
MS Works Suite 2004
SoundBlaster Audigy 2
Dell Jukebox PLUS (kind of like iTunes, but not really)
Dell Picture Studio Photo Album Premium (ditto, but for iPhoto)
RealOne Player PLUS
Dell Gigabit Ethernet
Total cost: $1,500
Pros: No Panther, but much closer to what a single G5 is in terms of options and expandability. Software is also closer. Better graphics cards and optical drives, but that's nothing new. Also comes from a company that is actually making a profit, like Apple is.
Cons: It's Windows.
Neither uses SATA drives (slower, but higher storage, and cheaper parts), and all three machines (your HPs and the G5 1.6) use the same RAM, but the G5 has four slots and the PCs have two. The HPs are slower networking (no gigabit), have one fewer PCI slot, are harder to get inside to work on, have no internal 802.11 antenna, and no Firewire 800.
At least one of your claims is completely fabricated. How many others are?
Next!