WNDR3700v1-slow speeds with wired connection

[wevie]

I have a WNDR3700v1 router and have a problem with it. The wireless is great and always reaches the max speeds I pay for when downloading or uploading. The problem is with my wired PC. The upload is fine but the the download seems to be throttled to the point that things will not download at all and will even timeout in many cases. My max download speed is 1.4Mbs/sec and it will reach that if I hook straight up to the modem but when going through the router, it will only download at about 40Kbs/sec at best.

If it matters, the PC is running Vista (ya I know), has 4Gb of RAM and the CPU is an AMD 64 x2 dual core 5000+ running at 2.60Ghz

The modem is a Motorola Surfboard model SB510

Thanks to anyone in advance who takes a look at this.