The link I posted is most definitely a machine for gaming, since it doesn't have a separate graphics card. But I can testify that the board works very well for 24x7 use, with the exception that the original chipset fan should probably be replaced. It is noisy and there have been reports of premature fan failures.

While working with the machine (normal X dekstop, coding and compiling) I have run USB-to-USB copying and at the same time read ISO images from DVD to disk, and for background "noise" run quite aggresive regression testing of some software.

What I am suggesting is that you should look at different hardware from what you are currently running. Both Linux and Windows XP (I can't say I have enough experience with Windows Vista yet since I hate the bloat) should handle USB with ease as long as there isn't a problem with drivers in relation to the USB or IDE controllers/chipset. I'm saying that you are unlucky with your specific machine, but that it isn't representative for a PC-class machine running any major OS.

The above link was a suggestion for a very low-cost utility machine with low power consumption but still reasonably recent hardware to be quite useful. It can be run as main machine for a non-gamer. But it is excellent as a utility server. 6x USB 2.0 external disks would allow up ti 9TB for a cheap file server. As long as HD material isn't needed, it could be used as a media center for DVD and music. It works well as a mail or web server. With a 4-port network card in the PCI slot, it would work great as firewall for a small company with need of one or more DMZ for servers. With a data capture board, it would make a reasonable measurement collecting server. The hyperthreading and dual-core is advantageous when getting quick response times in a multitasking environment. But the machine isn't magical. Just about any normal PC should do well. This alternative is just a bit cheaper, smaller and less power-hungry when you don't need a dual- or quadcore 3GHz machine.

Tell you what: Take a USB disk to a friend and ask them to demonstrate a multi-GB transfer and you will most probably see a constant transfer rate without any lockups (unless you happen to have the USB problem in the USB disk or a broken USB cable). The graphical front-ends of our OS gets more and more visual bloat, but the underlying engine shouldn't have any problems keeping up with the hardware. If you had visited me, I would have been able to demonstrate a 100GB transfer from a networked machine to a local USB disk (or reverse) and you would have seen a very nicely pegged network transfer graph continuing for GB after GB of the transfer.

I'm no guru at configuring machines, but I have been using and owning quite a lot of machines without seeing your problems, so the deduction must be that you are unlucky to have an unsupported or badly supported device, or something that is broken. I realize how hard it is to pinpoint where the problem is, but it isn't representative for todays hardware or todays operating systems.