I'm with Harry; I know it sounds superstitious, but almost every time I've used Linux to write to an ntfs partition, I've ended up having to run chkdsk on it. Especially with multi-gigabyte files, like disk images. A gazillion people will tell you that I'm wrong; that using the ntfs-3g driver is completely safe. YMMV.

(As an aside, when the heck did the plain old "ntfs" driver become read/write?)

As Harry said, consider buying an SATA or IDE hard drive (they're cheap), and sticking it in an external hard drive enclosure with a USB or Firewire connection (also cheap). Format it as FAT32 (aka "vfat") and you're in business, except for the 4GB file size limitation.

If your BIOS is compatible, you could even partition the external hard drive (using, for example, gparted), install Linux on it, and boot from it.

Here's the mount man page. See The Linux Documentation Project for more information.

<edit> Since you posted about your virus problem before I got this post off -- if you've got a Windows computer that's directly connected to the Internet, you absolutely must have a firewall (either software-based, like the free ZoneAlarm, or, even better, an external router that sits between your DSL or cable modem and your computer, and does NAT -- or even better, both). (You can also set up an old computer as a router using a specialized Linux distro.) And you absolutely must run always-on anti-virus software, like the free avast! antivirus.

My brother once got infected with a worm while using Windows and a 56k dialup connection. I kid you not.