Aright just so you know man, your FSB is 266 and your RAM is rated at 333. Your FSB in the BIOS is set to 133 I know...but RAM is DDR which means DOUBLE data rate, so you have to multiply that 133 by 2 when figuring out ram speeds. So your CPU has a FSB of 266 and so yes your RAM is running at 266 which is PC2100 speeds. I have a 2400+ in my secondary computer and was running PC2700 and PC3200 RAM ok. But yes it is creating a bottle neck. Well it's not creating a bottleneck if you run your RAM at PC2100 speeds. Then you'd have a 1:1 ratio with your CPU and RAM, but the RAM isn't performing at the speeds it's supposed to.
Don't upgrade to an Athlon 3000+ just to get an FSB of 333. You might as well get a 400FSB chip like the 3200+ that way you can upgrade to PC3200 RAM in the future. Alternatively you could get the mobo and CPU that I have (check my sig) and you can overclock this 2400+ XP-Mobile to 3200+ Speeds for half the price, but you also need to know what you're doing