Expanding logical disk without erasing?

[chetal@gedny.ml.com (Pradeep Chetal)]

Hi,

I partitioned my TP750Ce's 340MB disk so that it has 120 MB (240 MB
compressed for DOS) and 220 MB which I thought will use for Linux.
However, I Might get another PC for Linux. So I would like to expand
TP750 disk to be used as C: disk. Is it possible w/o erasing everything
on it already? I do not want to call the 2nd disk as a D: or something else.
I rather keep it simple C:.

In adddition, what does 486 SL-Enhanced DX2-50 mean? The Thinkpad
crawls on every application I run - like Mathematics, Lotus, etc. 
How can I make it faster?

Thanks,

/Pradeep