What is the "best" laptop brand of these?

[Jenny]

Hi there!
So if I'm accepted to my choice university, I'll be needing a new laptop. Mine will be a little over 2 years by then, and it's kinda slow.

Actually, is it even worth it to buy a new one? I've got an Acer Aspire 5100-3123, with 512 MB of RAM, running XP. I think the processor is "AMD Turion 64 X2" but I'm not sure. It can get kinda slow though. :P

Anyway, if I will be buying a laptop, which is "better"?
Acer, Asus, Dell, Gateway, HP, HP (Compaq), Sony, Toshiba?

Acer: Aspire 5535/6920/6930
Asus: M50VM-X2
Dell: Inspiron 1545, Studio 15
Gateway: M6882-h
HP: G50/G60, Pavilion dv6-1030ca
HP (Compaq): 6730s, Presario CQ60
Sony: VGNNS140DS VAIO NS Series
Toshiba: Satellite A350-05N/L300-07R/L300-0G1/L300D-03K, Satellite Pro A300-012, Tecra A10-00R/A10-00S

I'm not asking for a review on each, haha, but I'm just giving you what's available to me and seeing if you guys have opinions on any of them.

Thanks!
Or should I get a Mac? Are they a lot better...? I'll be using it for MSN, iTunes, Facebook, Word Processing, etc.

I don't think I'll need to buy any programs for university. It's Waterloo's Math/CA program.

[TlSmoak]

get a mac