Renewing a Late 2008 MacBook Pro: hard drive and battery substitution

Question

Hi all,
I am an happy user of a late 2008 MacBook pro.
However, with the passing of time, it became slow and the battery also deteriorate (it still quite OK, but it is not like at the beginning).
But let's start from the beginning: the hard drive
By googling for a while, I noticed that several people experienced very slow performance of their late 2008 MacBook Pro. That is also my case. Apparently, this is due to the hard disk which is dying, and then I considering to change it. However, I haven't found answers to these questions:
- Is it possible to mirror all the containt of the current disk to the new one?
- I only have the original installation disks of the first Leopard. I made all the updates through the network. Moreover, since it passed lot of time, I am afraid that some sector of the installation disks may be damaged. This means that I may fail in the installation of Mac Os X on the new hard drive. If I have to reinstall everything from scratch with the new hard drive and without installation disks, how should I do?
- If I go a Mac Reseller shop, will do they perform this operation? And how much does it costs to make it? Or I may also go to some generic computer reparation guy?
- Is it convenient to save all the data (movies, documents, pictures, emails, etc) somewhere (e.g. external HD) and then perform a completely new installation?
Next, let's consider the battery.
Here is a screenshot taken with iStat Pro:
Do you think it is worth changing it? From System Profile I have those other info:
  Full charge capacity (mAh):          3386
       Current (mA):          846
       Voltage (mV):          12029
  Condition:          Replace soon
What do you suggest to do then? How much does it cost a new battery? Actually, I think that also the processor performance deteriorate (it often becomes very hot, especially when watching Flash or Silverlight stuff), but, unfortunately I cannot change it.

Answer 1

Hi!
Thanks for all the answer. Please let me to resume this old and interesting discussion.
After having evaluated several solutions (including NAS, different ways of backup, etc) I bought an external firewire HDD, since I believe it nicely fits my necessities. Next, after these holidays, I will finally replace my old HDD with a SSD one. I think 120 GB are ok. I just need the apps and small-sized documents (rather LaTeX, Matlab, word, pages or excel documents, etc. - no movies or mp3 (I have Spotify, for that) ). Large files (e.g. movies, pictures, etc) may end up in external firewire HDD.
Now, let's consider the OS. I currently have 10.6.8 and I am very satisfied of that. I find it very stable, and all the apps I need are still well supported. On the other hand, given that there are like 5 years that I have the same installation, I may have a lot of obsolete files and setting that I can safely remove. This means that once I will have performed a backup of my documents, my email, my pictures etc. I can safely throw away all the rest. Hence, I may perform a brand-new installation of the OS. Although I am happy with 10.6.8, I was wondering if it is worth to upgrade it (I have a 2.53 Ghz Intel Core 2 Duo - 4 GB 1067 Mhz DDR3 RAM) to Lion, Mountain Lion or Mavricks. In that case, which would be the real benefits? And what about the cons?
Finally consider that I only have the Leopard installation disks from 2008 (not even Snow Leopard) and I will bring my laptop to a techician to change the HDD (I know, it is simple but I don't have all the screws etc. and I will not buy them only for this purpose). Once he will have replaced the HDD, will he re-install the OS also? Or I have to reinstall the OS through my original DVD (5 years old, I don't even know if they still work) and upgrade to Snow Leopard again by myself? I would exclude the carbon copy solution since I may want to throw away a lot of garbage and perform a brand new instalation of the OS. How to proceed? Thanks again!