Not at all, but given that you're using a laptop, your upgrade options are extremely limited.
Here's the basics:
-Internet Bandwidth: This will affect your streaming video framerate, choppiness, buffer times, etc. If the movie often stops to buffer and allowing the entire movie to pre-load before watching it gives you smooth playback, then Bandwidth is your issue; get faster internet or pre-load all videos from now-on. If pre-loading the movie does not help, then bandwidth is not your problem.
Watching higher quality (resolution) requires more bandwidth. If your bandwith is a problem, then try to stop doing anything else that requires bandwidth when streaming videos (close down any downloads, torrents, or other P2P programs. Don't browse other websites while streaming. Or, let the whole movie load before you press play. ) If that's still not enough, you can try watching at a lower resolution (for example, on youtube instead of watching at HD you could set it to 480P, or lower. )
-Processor speed: The computer can only do so much at once. If you've got a bunch of programs running in the background, close them down and see if that helps. Try to be ONLY streaming video, not browsing the web, burning a disc, etc etc. The price to upgrade this will vary wildly because it's a laptop. The maximum power, heat, speed, and type of CPU is dictated by the motherboard. You may be able to gain something here, but it's hit or miss. Ebay would likely be your best bet.
-RAM: Like the processor. The more you do, the more ram you need. If you do upgrade something, the RAM is likely the easiest and cheapest option. However, increasing the size of your RAM will only help if you don't have enough. The speed and type of ram is dictated by the motherboard, so you may be able to buy slightly faster RAM but don't expect huge gains (unless you currently don't have enough RAM and the system is swapping to disc)
-Graphics: Modern GPUs do provide hardware assist to video decoding. If the streaming video is being played in adobe flash, right-click the video then click settings, then on the Display tab (usually the first tab) see if "enable hardware accelleration" is checked. Some older GPUs don't work well with hardware accell, so if it's on try turning it off, and if it's off, try turning it on. Use whatever works better. Upgrading the graphics on a laptop is expensive, and again limited by the motherboard. To be able to upgrade the graphics, the laptop must use an add-in card type graphics and not an on-board type. We might be able to figure that out if you provide detailed specifications and model number of your computer
Sometimes, windows will get slower over time as programs are added and removed, and a re-install of windows might gain you some speed back.
Upgrading anything or reinstalling windows isn't something you should do if you don't know what you're doing (unless you're prepared to do a lot of reading up on it and can tolerate the possibility of making the computer temporarily or permanently unusable). Furthermore, since it's a Pentium 4 based laptop, you'd likely get better value for money by just buying a new one (you might be able to find a cheap used one, but always try to test it out to see if it's fast enough for your uses before you buy), unless you can get a hold of compatible used parts for very cheap (eBay, an unused similar laptop, computer repair stores, etc. Sometimes schools or businesses will auction off or give away their old gear when they upgrade, and that can be a good source of free or very cheap older components or complete computers.)
EDIT - also don't forget to make sure that you're using the newest version of flash player, and an up-to-date web browser, and system drivers. If you have a lot of toolbars or addons running in your web browser, turning them off might help a little bit