Question on DDR2 size/type in Notebooks

[paul48]

I've posted in Hardware topic, but optimum RAM size/performance affected by OS settings also

I bought a Dell Inspiron 640m in Oct 2006 with the then brand new T7200 CPU with 667MHz FSB, instead of the 'base' 533MHz FSB. At time of ordering, it didn't occur to me to check if the DDR speed should be altered to match the faster CPU, so the default 1GB of DDR2-533MHz, was supplied.
Given that I ordered a faster CPU than in the base model, the machine has always seemed slow, often freezing for 30 secs, which looking back, may have been due to a faulty HD which expired early.
In my early attempts to locate the source of the slowness, I installed the CoolBeans applet to give a small onscreen display of CPU, RAM, and 'Swap' file usage (it agreed with the MS Performance Monitor but more convenient). After a few hours of net surfing the machine becomes unbearably slow.... the RAM usage climbs from about 49% to 93+%, and the 'Swap' from 18% to 65+%. Current Solution: frequent reboots. The OS is WinXP MCE. I used Firefox-v3. I know early FF 1.5 & 2 had a reputation for large Memory footprint, but being so much better than IE, keep using it, and heard the Footprint/leak problem now fixed, - but maybe not ?

The MS 'Performance' settings are: CPU & VM priority=Programs Virtual Memory settings: C: 1524-3048MB. I read WinXP needs 15% 'free disk space' on c:, so kept 15% free and used Defrag monthly. I was recommended to try a 'tune-up' tool called Advances Sys Care V3. It made countless changes, but laptop no faster. I since read, to speedup it is better to upgrade CPU or RAM, as tuneup tools don't help.

I heard there is a MS tool to defrag the registry maybe worth installing, and a MS tool to make the Pageing File Contiguous.
Also saw a recommendation (Win7) to use D: rather than C: for the paging file. In my laptop, both C: & D: are the same physical drive. Is D: better ?
Although 3 yrs ago I was told 1GB ample for WinXP and can't handle more than 3GB, all I see in reviews since are recommendations to fit 3-4GB. Also need to account for a sizeable chunk of that 1GB is used by the Intel 950 IGP, not available to the OS. What is your view ?

Regarding the DDR2 I have 2 questions: Can the above (Centrino-1) system work, and benefit from faster 667MHz DDR2 ?
will the system benefit from more, say 2GB of 667Mhz DDR2 ?

I would prefer to see the RAM use down around the 25% (Coolbeans) figure I have seen on various Desktops

Although maybe not good value, can this sort of laptop benefit from fitting an addtional small SSD disk, in say the ExpressCard slot, to be say the Paging-File, or maybe more ?

If so, what size of SSD is reasonable ? I partitioned this 160GB HD into C:60GB, D:90GB but now wish it had been 90/60 !

As about to post this, I see an article in Computerworld on Xp>Win7 upgrade which mentions the Crucial Memory Scan. The Scan is crude but says I'm getting about 75% of the perfomance I would have, if I replace my 2 x 512MB DDR PC2-5200 with with 2 x 2GB PC2-5300. I guess this answers my question should I have matched the memory speed to the faster 667 Mhz FSB of the T7200: Yes. It also confirms a 3GB limit for winXp, but as unlikely to change from winXP to Win7 unless forced to by Apps, the Scan doesn't tell me what improvement I would get due to a) 667MHz FSB, or b) doubling memory ro 2GB (it says I am losing 25% due to NOT having Quadruple, at the faster FSB).

Thankyou for any answers on the above