Should I get a blu ray internal drive or external for my HP laptop?

I am kicking myself in the butt because I didn't add a blu ray burner on my computer when I ordered it last year. Basically, I have a TIVO HD-XL and I want to transfer my recorded shows to my computer (done already), edit the commercials and segments I want out of them (done already) and burn them to a blu ray disk with PowerDirector9 Ultra. I used something called TIVO Decoder GUI, and it converts .tivo videos into .mpeg2 which is wonderful. Everything is going well, except that I forgot that I don't have a blu ray burner (I have a regular dvd burner). Which is better for me? I want an internal one so I can just do the burning and watching right here on my laptop, but they're saying that barely any of them are compatable with an HP computer because of the size or the SATA or something like that... An external sounds great, but I don't know... My laptop is the HP Pavillion V6 Entertainment PC (dv6z-2100) (I custom built it on HP's website) and has about 500GB of memory on it, and 3GB of RAM. I heard something about an optical card or something, and having to switch them...I don't even know about... Can anyone recommend an internal one that works great? Or external? I have a PS3 and a blu ray player, but it would be nice to play them on my computer. I can't get a new computer, because I just got it last year and haven't even paid for it yet (I didn't steal it, I used bill me later).