Will this make my computer faster?

[FunkMaster66]

I like to play cs and half life 2 and when i click on the games for them to load up they take sooooo long and between loading times it is really long. My comp slows down and it becomes weak. I have a sempron 2500+ and a radeon 9600 videocard with 512mb ram. My hard drive however is only 20 gigs and it is almost full i only have about .5 gigs left. It is an old HDD too it has 4500 rpm and i think it is a maxtor my friend says. I want to buy a 160 gigabyte Seagate HDD with 7200 rpm and 8mb cache. Will having this new Hardrive make my comp a little faster even? I thought my sempron is compared to a celeron 2.5 ghz but it doesn't feel like 2.5 ghz it seems slower. I need a new hard drive anyways so will this harddrive make my comp faster? What other things can i do to make my comp faster?
thanks i'm a noob at comps my friend who moved away helped me build this but now that he's gone i dont know what to do.

 

[Trotter]

First off, your hard drive is too full. Windows needs room for virtual memory on the drive.

Here's a little list I put together:
http://techist.com/showthread.php?s=&postid=534983#post534983
Read it and follow what it says.

Getting a larger HD would be a definate plus. 7200 ARPM and 8MB cache will make you think your comp is running nitreous.

 

[GoodNews101]

I would highly recommend another stick of 512 RAM. That Seagate will do you good.

 

[FunkMaster66]

Ok I will try this. I hope it will make my comp run like it is meant to be ran thanks peoples.