Heyyyy Wacky!!!
For what it's worth, I'll try to add some personal findings/comments to things not yet replied upon. For all the rest, I fully agree with everything what Albert has said.
The reason why people say that their laptop/pc starts to lag or slow down after a while is mostly because they don't do proper (software) maintenance on a regular basis. I always say a pc/laptop is like a big industrial machine: without proper maintenance they tend to brake down. But with proper maintenance they can last a lifetime so to speak (unless it falls on the ground
)
It has nothing todo with the hardware, but all with the software and installed apps, especially all the extra (crap) people often install to make their PC faster/cleaner. Such tools quite often have the reversed effect. Regulary cleaning out temporary files, properly uninstalling unused stuff, and cleaning the freshly installed OS from many of the unneeded pre-installed crap that always comes with each laptop/pc, etc, etc, goes a very long way. So these stories of lagging/slowing down after a while haven't got anything todo with what brand or model you choose.
As for HP, I have had several HP PCs and a budget HP laptop, although I haven't used that laptop that much, I never realy had any problems with it. But as Albert said, there are horror stories for each brand though. (and quite frankly, I often tend to believe that a big factor/culprint in those horror stories is actually the person using the laptop).
Albert is correct in saying that these days laptops are made to be budget friendly instead of long-lasting. But my experience is also that these days there are no realy "bad" bad brands anymore either. Ok, there are some top quality brands, true, but you pay for it too in that case. But in the budget friendly category, it usually is all very similar quality stuff though.
As for Intel vs AMD, personally I'd choose Intel. But that is also because I don't realy have that much experience with AMD. Though, I never thought of Intel as 'overpriced'. Also, in my experience, you have a bigger choice in brands and models with Intel processors than with AMD processors, but that is maybe because AMD is less 'popular' in Europe, dunno.
A 1/10th in GHz difference is nothing. More important is the processor itself (for Intel: Core 2 Single, Core 2 Dual, Core 2 Quad, Core 2 Extreme mobile. And the newer i3, i5 and i7) and not to be forgotten the amount of memory of course (I'd suggest at least 2GB - ps: anything higher than 3GB is only usefull if Windows is 64bit).
I guess it just comes down to specs and then comparing prices of different brands. If you have a good feeling about Toshiba, then by all means stick with it and/or keep it in favor over other equaly priced laptops with same specs from other brands. Toshiba is certainly not a bad brand.
eg: My sister's (the vet
) old laptop was a Toshiba too and now she has again choosen for a Toshiba (better specs, newer model). She hasn't had any problems with it yet and she takes it with her on the road sometimes, so...
/ 
