T61 is a fine machine!
I fitted an SSD to my desktop - that speeded up boot-up from several minutes to under a minute.
The only mistake I made was choosing an 80GB SSD. I had to shuffle stuff off the old C: drive to get it under 80GB before the drive cloner would work. I put all my "stuff" on drive D and told the software to look there for it. Most obeyed, apart from Apple, which churned the SSD rotten till I got fet up and symlinked it all to the "Apple" drive - drive G (for "gotcher!).
If I did it again, I'd go for a bigger SSD.