Isnt that the point of upgrading? I mean why upgrade if it will only last you a few months?
PCI-E is the next Gen of Video card interface, just like socket 939 is for AMD CPU's.
The wise thing to do when considering upgrade uptions is not to find the cheapest alternative, but the most cost-effective for the long-run.
Get PCI-E because next time you upgrade, you don't need to get a new motherboard too, unless you work at a computer store and can return things for full value a year later...