SPCR

i have one of these units with a bad hard drive and im wondering if its worth upgrading. it comes installed with 1g ram but upgradeable to 2gb and im not sure if the unit will show any performance boost due to any possible limitations. secondly is the bad hd that needs replacement. western digital scorpio blue vs black and bevt vs bpvt or advanced format tech. will i see any performance boost with black over blue and or the aft

There's no such thing as general performance.
You've got to look at your usage to determine what's the relative importance of bottlenecks.

You have a weak single-core CPU. I wouldn't want to work on it all day but it's OK for many uses like writing, checking emails, browsing text-based sites and so on. If you like the weight, the format and the keyboard it could serve you many years as an ultra-portable laptop if you need to take notes at conferences or something.
Your laptop likely has very low power consumption (depending on the AC brick), making it suitable as a very small file server.

What you want to use it for determines what drive would be best.
If you want to use it on the go and want fast response time, a small SSD would be ideal. You typically don't need much disk space for the kind of applications you'd want to run on such a weak CPU. SSDs have no mechanical parts and survive accidents.
If on the other hand you want to use it as a file server, you probably want a slow high-capacity drive.
Considering the prices of small SSDs, I don't see much point in a fast spinning drive but maybe you have an application I didn't envision.

I've repaired many old laptops with very cheap used hard drives. Some of them didn't last very long and some of them are still working after years of heavy usage. YMMV but for a slow laptop, the price is right.

basically im wondering if this unit will benefit in speed from the use of a western digital black over a blue or any faster spin (7200) vs (5400) hard drive? then there is the new advanced format technology. also, will the extra power consumption be a factor as well? heat may also be an issue as to why the seagate momentus 5400 failed in the first place. another thing that is off the title topic is the ram. would a 2 gig stick really make a noticeable difference? after all this is a pretty basic unit with a slow cpu. any ideas?

Feel like copy-paste HFats comment right here.

Again, it depends on how you use the system. For most users I don't think bothering with 7200RPM high-performance drives is worth it. Get an SSD unless you need a lot of space for some reason.
2GB RAM is always nice. I would probably upgrade if I could find a cheap 2GB stick to put in there.

im trying to keep total cost under 100$ so the ssd is probably not an option i found 2gig ram sticks for around 25-30$ and ill have to wait for a sale on a decent 5400 hard drive. any ideas on this? reviews were not so great on the write portion
http://www.newegg.com/Product/Product.a ... 6822145530

what is the drive thats being replaced?

seagate momentus 5400.6 250gb

these options on ram are all priced well, any top choices? i like the heatsink gskill's, will they fit?
http://www.newegg.com/Product/ProductLi ... ageSize=20