Temperatures on my work/gaming machine

[Modred189]

I have a emachines computer with:
AMD Athalon64 3500+
ATI Radeon X700Pro (PCI express)
2G DDR Ram
Added a 430 watt Antec PSU (replacing the stock ~250/300

I was seeing some high heat temps (EDIT: Temps measured with CPUFan) with the built-in CPU heatsink/fan so I purchased an antec replacement with a copper heat sink and larger fan. While I did see slightly cooler temperatures, I still run (under load) at around 65 degrees. I assume is this on the high side, and was wondering if there was anything I could do (on the cheap) to get those temps down. There is one case fan, blowing outwards.
I was wondering if adding a fan to the case door myself would help. If so, should it be an intake or exhaust? 80 or 120 mm?

Also, all of my PCI and PCI-E slots are full (X700Pro, wireless card, TV tuner and sound card. The wireless card is closest to the video card, as it is the smallest and allows for the best air flow to the X700)

Could it also be that I used the thermal paste that came with the HS/fan?