So I finally settled on a new computer and I got all the specs figured out except for the HDD. Currently I'm stuck between two: a 128GB SSD and a 256GB one. Normally I'd go with the bigger one but it's $360 more and that's a lot of coin. However I plan to dual boot with Win7 and Lion and I assume that means I'll have to partition the HDD and I'm not sure the smaller one will cut it. I don't plan on keeping much else on it except for programs and a couple of games and I have plenty of external HDD's for music/movies but I also don't want to constantly worry if I have enough space. My current HDD is 320GB and only about half full.

The extra coin isn't worth it. SSDs will get cheaper, faster and bigger in the future, so I would't invest in a big SSD just yet. The SSD I would recommend(if you have a 2011 MBP) is a Vertex 3 120GB.  
 
If you have a an older one I would recommend an Intel 320 or a Vertex 2.  
  
Also, do you really need to dual-boot? 
 
Edit: I think I may have read it wrong, are you buying from Apple? In that case, go for the 128gb option I guess.  

Yup, I'm ordering it next week. And dual booting is the main reason why I chose a MBP so, yes, it's rather important to me. Anyone with Bootcamp experience know how big the partitions have to be?