changing your PC is quite good,but not really compulsory ,because even after you change your pc,if u still open emails that appear to be from and click on any link in it ,it would expose you to same problem,
do these things 1,formate your PC,never ever click on any emails that says its from and wants u to update your account by visiting some links,for your info , would never send u any link by email ,or any attachments,when u get any email with these stuff ,don't click on any link in it ,
2,i don't know if you have set your account security settings to high,though i suspect you have not done so ,if you do this ,anytime u log into your account ,the one time pincode must be sent to your email account on file in your account profile,and this pin must be entered before your u or anyone gets access to your account on that PC from whicyh u have tried to login at that point in time .
let me make it clear that even in a situation where keylogger have been installed in your system,if u have set your security level to high ,the scammer would still not be able to get access to your account,because anytime he enters your login details correctly ,the pincode would be sent to your email id and the oneway he would be able to get access to your account is if he has access to your email id for him to able to get the pincode .
now here is what u should do,formate your PC ,install antivirus,antispyware and firewall.I use avg commercial edition,you can contact me for the license code to crack it

or it will be disabled after 30 days

, for antyspyware i use avg antyspyware commercial edition too,again if u want to use it past the 30 days trial,then contact me for the code

, then go for the free or pro edition of zonewalarm firewall,if u opt for the pro edition it would work for 15 days free and then revert to free edition ,to continue using the pro edition ,contact me for the code

do not ever trust the windows firewall as its almost useless ,i have tried it and confirmed that it hardly protects PC from anything .
Finlay but not the least ,don't use free email for your account,don't use companies like yahoo and hotmail ,these are easily hacked and your pincode will be exposed ,rather use gmail if u must use free email or ask your service provider to provide u with one ,those are more secured than the well known yahoo and hotmail which attracts the attention of most Naughty Boys

OH i nearly forget ,do not use same email id u use for account for other stuff like paid email and so on and don't use it to post in forums either,if possible ,use it only for account,also check that email from time to time (daily is better) to see if u have any notice from about account profile update that is not authorized by you ,this always happens when someone tries to check account security details.
i hope these would keep u more secUred with your account than u used to be.I do not claim that these would keep u 100% safe (this is never possible online) but will keep u safe most times and greatly minimize your exposure to getting hacked .