I'm buying a new laptop and still have lots of videos, pictures, pdfs, and code etc on my old laptop. At least 30-40 gb. What's the most effective way of transferring these?
Passport HDs are very cheap right now.
If the time it would take to copy isn't an issue, then I'd put both laptops on a network and use SyncBack (it's free) to copy the files from one to the other. I don't what you have in terms of networking, but wirless is one route or has been suggested, a Cat-5e coverover cable will do. There's an example on the Microsoft site on how to configure Vista for it for example (you don't mention what OS you're using, I'm assuming Windows).
Alternatively you could buy an external USB drive and copy them onto the drive from the old drive, then from the drive onto the new laptop. That would be slightly quicker than network transfer.
The transfer may be much faster using an external hard drive casing, especially if the new laptop PC has an e-SATA port (and the HD casing as well of course), than any solution involving an ethernet cable. Basically, external drives connected via e-SATA operate at the same speed they would in a internal setting. USB2 is much slower, but I've read USB3 was supposed to have similar performance to e-SATA (I'm not up-to-date on this).