RAM? Your spec is virtually identical except i have 2GBs of ram and a 128mb graphics card. Also What hard drive do you have? Mines a 7200rpm ATA with 8mb cache. slow ass 5200's can still be bought and they will increase loading times noticably.
Lumpeh, same HD as you...does FH skip for you? If not, then I'll spring for more memory. What's your sound settings on? You have it set at 22khz?
I have mine @ full quality software with 64 channels. i run the KX-Drivers rather than Creatives own. They arent gamer orientated, but theres no speed lost with em and you only lose EAX which is just a bunch of DSP settings, still get the essential surround in games.
Blackknight ran very slow when i played it, but the other maps run fine as far as i can tell. Generally on our specs, when things run slow like it does when theres loooads going on, theres little you can do because its just the way BF is coded. :( if you have the cash, the extra ram might not be a bad idea. ;) i havent checked to see what full load of FH takes up.
Even on my 1.4 Centrino and 512mb SDRAM and a ATI Mobility Radeon 9200 I rarely lag after the engine warms up.