Would I be correct in thinking that your computer is an IBM Thinkpad from around 2003?
If I am any upgrades you could make will be minimal with increasing the Ram to 1GB (2 X 512MB sticks) and a larger storage capacity HDD your only real options.
As the graphics chip is on the MB it also uses your system Ram hence the choppiness problem with any video you watch, increasing the amount of system Ram to 1GB would help this but the improvement would not be breathtaking.
Should you decide to try the additional Ram please be aware that it is better to replace the existing Ram with a matching pair of 512MB sticks, below is the Ram information required for upgrading;
•64-bit Double Data Rate (DDR) non-parity SDRAM memory
•PC2100 at 266MHz
•Two 200 pin SO-DIMM memory slots, one slot is pre-populated with 128MB or 256MB, leaving one socket available
•Supports up to two 512MB SDRAM SO DIMM
•Supports maximum memory up to 1GB
I hope the above information helps you to decide what you consider your best option.