It's most important to look at what you want to store on your local disk. I think a 64GB drive can fit Win7 but the more applications and documents you load, the closer you will get to filling the drive. I would recommend looking at a 120/128 - Crucial, Intel and Samsung are all incredibly reliable drives. I would probably recommend the Crucial because your laptop won't have SATAIII ports so you're looking at 260MB for max read/right speeds for most SSDs. The Crucial will not max out your write speeds, but it's still good enough to notice a significant improvement in load times.
I personally use an 120 GB Intel 520 in my desktop and a 128GB Samsung 830 in my laptop - both are feel quick and I have not had any driver incompatabilities and minimal maintenance tweaks.
Make sure your BIOS supports AHCI or you're not going to get that much speed benefit from any SSD.