USB 2.0 Card advice needed

USB 2.0 is pretty standard these days so you don't really have to worry about buying from some 3rd party brand - its at that point where manufacturer's have to try to screw it up to screw it up.

If you get a PCI USB 2.0 card, yes your external HDD's will run at full speed (whatever that may be). USB 2.0 has a theoretical max of 480Mbps = 60MB/s and your PCI bus has a limit of 133MB/s so you'll be fine. The "best transfer rates" will most likely depend on your HDD, not the USB 2.0/PCI interface.

As for points to look out for, if you have front panel ports, some cards will let you hook the front ports into the card to get front panel USB 2.0. Other than that, just the number of ports it has. I got a 4 porter and it works great.

Its an I/Ogear one - no problems at all. Works perfectly w/ my XP Pro. I'm sure the bigger names wouldn't have issues either, like belkin or whatever. If in doubt just look at reviews when you're shopping around. XP Pro shouldn't have any driver issues. Plug and play!

I think i have this one but you can probably find a cheaper one somewhere else:
http://www.amazon.com/gp/product/B [...] 42?ie=UTF8

Oof I see your point. You might have looked at this review:
http://www.techreport.com/reviews/ [...] ex.x?pg=17

Where it shows the chipset's Read at ~17MB/s and Write at ~11MB/s.
(Of course realize that USB 1.1 would max out at 1.5MB/s to put it in perspective)

Your computer has the Radeon Xpress 200P chipset, as stated here:
http://h10025.www1.hp.com/ewfrf/wc [...] =c00298365

Now your issue - how to bypass the motherboard USB ports...
I would say that getting a card should help. The review seems to point at the USB controller on the chipset that is the problem. If you got another USB card and it still performed as slow, then the problem would be with the southbridge of the chipset (see pretty picture http://www.digit-life.com/articles [...] sets.html)

But a new USB 2.0 card will have its own USB controller so you should be fine because its connecting through the PCI interface via the southbridge. Moreover, since the SATA ports are hooked into the southbridge and are not constrained to the above speeds, it would seem that the USB controller is at fault.

So, IMHO, if you get a new one, you'd probably see a speed increase.

The maximum speed for an external device connected to USB 2.0 in High Speed mode is theoretically 42MB/s because of the additional bits required for the communication protocol (USB devices are always slave, it's the host that asks to them to supply data when it can receive), error correction and diagnostic functions.
This with a serious realtime OS or under Linux boxes. Under Windows the maximum effective speed trasfer rate is limited to 30-35MB/s, due to Windows total inefficiency.

Anyway, the fastest Flash drives don't go faster than 20MB/s: it's a limitation of the flash chip, you can't go over this.
Only with an external USB hard drive you can attain the maximum speed.