Microsoft just released some important updates for people using Vista and suffering from (amongs others) slow file copies.
938979 Vista Performance and Reliability Pack
This update resolves a number of individual issues which may be affecting some computers running Windows Vista. These issues have been reported by customers using the Error Reporting service, product support, or other means. Installing this update will improve the performance and responsiveness for some scenarios and improves reliability of Windows Vista in a variety of scenarios.
938194 Vista Compatibility and Reliability Pack
This update resolves a number of individual issues which may be affecting some computers running Windows Vista. These issues have been reported by customers using the Error Reporting service, product support, or other means. Installing this update will improve the reliability and hardware compatibility of Windows Vista in a variety of scenarios.
938828 XP Explorer.exe Reliability Pack
This is a reliability update. Install this update to improve the stability of computers running Windows XP. This update prevents crashes in explorer.exe.
These packs (actually, they are hotfixes) are downloadable via http://connect.microsoft.com/ or via the source http://www.neowin.net/index.php?act=view&id=41691