Upgrading laptop

You will probably want to check the manufacturer specs to see if any higher-end CPUs are supported. This Intel search is suggesting that the T7500 and T7800 will work in the socket you have, no guarantees that the Vaio's motherboard will recognize it though. Looking at amazon, the T7500 starts at $250, and the T7800 is over $300. I'm seeing cheaper offerings on ebay, but they appear to be used, unsure if that's a concern or not.

If you don't mind me leading you down a different path though, have you considered purchasing an SSD? While processors have some effect on how fast programs switch/load, a lot of it also has to do with disk I/O.

A processor upgrade is likely to be relatively expensive compared to the performance gains you get. An SSD will virtually eliminate program load times, and it will use less power (meaning longer battery life). It looks like your current HDD is 160 GB? If you're not already completely maxxed out on space, you could easily consider getting a 120 GB SSD for less than the prices I was finding. You could even spring for a $20-30 external case to turn your current drive into an external USB drive.

The 120 GB Corsair Force is one of the best on the market right now, and it's $220 ($190 after a $30 mail in rebate).

As part of this, you'd also do a complete reinstall of your OS & programs, which might also speed things up a little.

wow i am slowly realizing how important those damn hard drives are. i don't really want to spend the money for an SSD so i am thinking an HDD instead. are laptop HDDs different then PC HDDs?

Laptop hard drives are 2.5" form factor, which is not the standard desktop size.

I don't know that you're going to see a huge improvement moving from a WD Caviar Blue laptop drive to any other laptop drive, but it is certainly less expensive than switching to an SSD. I'm not as up on my laptop hard drive specs as I am standard desktop drives. However, you can get 500 GB drives for as little as $60 on newegg, and the 7200 rpm 500 GB drives start at $70. Switching to a 7200 rpm notebook drive might show some improvement, and it would give you a big boost in storage compared to what you have now.

If I can make a suggestion, though...do you have an Apple store near you? If so, go there and check out the standard Macbook, which will have a traditional notebook drive in it, and has a 2.4 GHz Core2Duo processor (faster than your processor, slightly slower than the $300+ T7800). Then check out the new Air, which has an SSD and the 13" model runs with either a 1.83 GHz Core2Duo or upgrades to 2.13 GHz (so, pretty much the same speed as your processor). If you notice a difference between the two, you might want to consider an SSD. If you don't see a huge difference, then forget everything I've said.  

And of course, if you just don't have the budget for a $200 SSD, then you should probably forget my suggestion anyway. You might just want to do a fresh OS install (after saving your data on an external drive) and see if that improves your notebook's response.