|I second the advice from Cobra, installing Vista SP1 should alleviate your data transfer issues. |
But, as far as the AHCI suggestion from kx5m2g, I wouldn't recommend doing that, at least, not on your system drive. This is because, you are likely to end up with the infamous "STOP 0x0000007B INACCESSABLE_BOOT_DEVICE" error right after changing -- the SATA mode -- from IDE to AHCI since your Windows install was completed in IDE mode.
IMHO, if your HDD does not support NCQ, switching from IDE to AHCI is most likely not even worth the hassle to begin with. Moreover, sustained SATA transfer speeds are not significantly that much faster than the older (IDE) PATA interface.
But, if you have an NCQ HDD & are adamant or will like to consider the switch to AHCI, you better take a look at this before doing that.